After months of speculation, former Barcelona midfielder Luis Enrique returned to the Camp Nou on Monday as the new manager of the Catalan outfit.

The 44-year-old, who coached Barcelona B from 2008 to 2011 before managing Roma, revealed at the weekend that he would depart his position as boss of Celta Vigo.

Gerardo Martino, meanwhile, mutually agreed to stand down from his role with Barcelona after failing to win a major trophy this season.

Enrique has signed a two-year contract with his former club and will be tasked with leading the Spanish outfit to the top of European football once more.

Here, Sports Mole has picked out five key areas that the Spaniard must address at the Camp Nou, in relation to this summer and indeed long-term.

1. Help Lionel Messi rediscover best form

Messi's statistics this season read 46 matches, 41 goals. By any standards, that is a remarkable total. However, in truth, it has been a disappointing campaign for the Argentine international. He spent two months on the sidelines either side of Christmas and has struggled to re-discover his top form in the second half of the season. More worryingly, the attacker seemed to go missing in the big matches when his team needed him most.

Granted he scored a hat-trick in the league win over Real Madrid at the Bernabeu, but he struggled in the Copa del Rey final against Los Blancos. The 26-year-old also barely featured in either leg of the Champions League quarter-final against Atletico Madrid, who seem to have found a way to stop the former Ballon d'Or from influencing matches.

There had been talk of a move away from Barcelona in some sections, but such claims have been quelled this week, with Messi signing a new long-term deal at the Camp Nou. The contract, which is his seventh new deal in 11 years, has made him the highest-paid player in the world. However, it has reportedly rubbed a number of the supporters up the wrong way, with Messi on the receiving end of jeers from some sections of the Camp Nou during the 1-1 draw with Atletico Madrid last weekend.

Despite his troubles this season, Messi remains, alongside Cristiano Ronaldo, the outstanding player in world football. If Enrique can get Barca dancing to Messi's tune once more, it will be a successful tenure for the Spaniard.

2. Transfers – incomings

There is no question that Barcelona, now more than ever, need fresh blood this summer. Long-serving goalkeeper Victor Valdes will seek pastures new, with Marc-Andre ter Stegen arriving from Borussia Monchengladbach seemingly as their new number one. A back-up stopper is also needed, however, with Jose Pinto not being offered a new deal at the Camp Nou.

Ahead of that, at least two centre-backs and a right-back are needed. Carlos Puyol, like Valdes, will officially depart next month, while there has also been talk of Javier Mascherano moving to Napoli. Right-back Dani Alves has had an indifferent campaign, meanwhile, with the Brazilian strongly linked with a move to Paris Saint-Germain. Established stars such as Chelsea's David Luiz, Manchester City's Vincent Kompany, Bayern Munich's Javi Martinez and Valencia's Jeremy Mathieu, who has been one of the best centre-backs in La Liga this season, have all been linked with moves.

A young centre-back is also believed to be a priority, with Athletic Bilbao's outstanding Frenchman Aymeric Laporte and Real Sociedad's Spanish international Inigo Martinez fancied by the new management at Barcelona. Further forward, a new central midfielder is needed in the mould of Juventus's Paul Pogba, although Arturo Vidal might prove to be a more realistic target for the powers that be.

It has already been revealed that Gerard Deulofeu and Rafinha will return from loan spells with Everton and Celta Vigo respectively to form part of the first-team squad. However, with Alexis Sanchez and Cesc Fabregas's future uncertain, a wide forward in the mould of Borussia Dortmund's Marco Reus could be needed. Realistically, Barca need at least five new faces this summer.

3. Transfers – outgoings

Outgoings have been touched upon in the section above, but the names mentioned only scratch the surface with the turnaround that is expected to occur. It is understood that Ibrahim Afellay and Isaac Cuenca have both been informed that they can depart, while there remain question marks over the long-term future of Cristian Tello, whose progress has been stunted due to time on the sidelines this season.

Defensively, Alves has reportedly been made surplus to requirements, while second-choice left-back Adriano, who has played a lot of football this season, could also leave. Further forward, Fabregas has been strongly linked with a return to the Premier League and if a figure of £45m could be gained, then Barcelona might be forced to part ways with the Spaniard.

Alex Song is another that has struggled for regular football since arriving from Arsenal, while Sanchez and Pedro have also been linked with a departure. Both forwards have had successful seasons in terms of goals, with Sanchez netting 21 times to Pedro's 19, but both have frustrated in the bigger matches. It is understood that Enrique will look to line up with Neymar, Messi and one more in attack next season and both Sanchez and Pedro will want assurances over first-team football.

Enrique must also sort out the futures of a number of the younger players in and around the first-team squad. Right-back Martin Montoya is highly rated in Europe, but has struggled for regular football, while centre-back Marc Bartra could find himself on the sidelines if, as expected, two new centre-backs arrive. Sergi Roberto, meanwhile, could also find himself sent out on loan.

4. Re-establish Tiki-taka football

Whether completely changing Barcelona's playing style was Martino's objective is a question that only he can answer, but Enrique must return the Catalan outfit to their basic principles next season. The phrase 'if it isn't broken, don't fix it' springs to mind and Martino tried too hard to put his own stamp on the team, which was not well received by a number of the experienced players.

Following the 7-0 aggregate loss to Bayern Munich in the semi-finals of the Champions League in the previous season, Martino felt that he needed to completely overhaul the tactics, which ultimately proved the wrong decision. The supremely gifted Xavi is in the latter stages of his career, but is still an incredible footballer. He spent periods out of the team during the 2013-14 campaign, however, with Martino looking for a different formula in midfield. As a result, Andres Iniesta's performances also wavered, while Fabregas, Pedro and Sanchez all drifted away after bright starts to the season.

Too often Barcelona were seen throwing crosses into the opposition's box under Martino, which was completely alien to the players that came through the academy. The lack of movement and interchange in the final third also made it easier for teams to locate Messi, who found himself coming deeper and deeper in an attempt to get involved in the match. Taking points off Atletico Madrid and Real Madrid was not a problem this season, with the Catalan outfit claiming eight points from their four matches against the capital pair. However, Martino simply got it wrong in games against the so-called smaller teams.

Tactics in general have been scrutinised perhaps more than ever this season, but Martino did not get it right during his tenure. Enrique knows Barcelona inside out, however, and indeed what is expected from the board and supporters like. If he can get the likes of Iniesta, Xavi and Messi inter-changing once more, it will spell trouble for the opposition.

5. Find Neymar's best position

Fairly or unfairly, Neymar has been criticised for his performances during the 2013-14 campaign. In total, he made 41 appearances, scoring 15 times. There were matches when he set the place alight, but other times when he flattered to deceive. There is no doubting, however, that he has the talent and temperament to become a star player for the Catalan outfit.

It has been a learning curve for the Brazilian this season, with referees not giving the 22-year-old as much protection as he would have had during his time with Santos. The experience will have done him no harm, however, and improvement will surely be seen in his second campaign. If Enrique is to continue with 4-3-3, which is expected, then he needs to find a way to get the best from Neymar.

The forward scored six times and registered eight assists in his first 14 league games for Barcelona, but off-the-field issues regarding his transfer from Santos and injuries took its toll. In 2014, he managed just three goals and zero assists in La Liga.

Martino, in fairness, showed huge faith in the attacker and when fit, he was selected in the majority of matches. Whether or not his position restricted his performances, however, is another question. He was deployed on the left in the majority of his first season in Spain, but struggled to produce his best work when opposition were allowed to double-team the attacker and force him into wide positions.

If Neymar is to thrive, Enrique needs to find a way of getting the Brazilian inside and linking with Messi on a regular basis. Whether that means changing formation is a question for the manager, but the former Spanish champions need to make the most of Neymar's vast talents.