Jose Mourinho was adamant throughout the most recent campaign that his Chelsea side would fall short where the Premier League title race was concerned. As usual, the mercurial Portuguese coach was correct.

This time around, though, it would appear that Mourinho will not accept anything but success. He's already spent big to bring former Arsenal midfielder Cesc Fabregas back to London from Barcelona, while a fee has been agreed for Atletico Madrid's talisman Diego Costa.

With the addition of the Spanish duo, the squad at Stamford Bridge is a strong one, but could still do with the odd tweak. Here, Sports Mole has picked out three further players that we believe would make the necessary improvements.

In terms of the left-back role, Chelsea have been spoiled since the summer of 2006. It was then that Ashley Cole swapped North London for West, providing the Blues with one of the world's best full-backs. Yet all good things must come to an end and following an eight-year stint, 33-year-old free agent Cole has completed a switch to Italian outfit Roma.

It was a departure that Mourinho was prepared for, though. He had identified that Cole's powers were on the wane last season, so much so that he often deployed right-back Cesar Azpilicueta in Cole's position. While Azpilicueta proved himself to be a more than adequate replacement, there were occasions when his need to use his stronger right caused problems, such as when he hauled down Sunderland striker Jozy Altidore inside the area with his right boot, when the tackle required a left-footed interception. Fabio Borini stepped up to score the penalty and win the match for the visitors, all but ending Chelsea's title charge in the process.

Luis would have no such issues, being a natural in the left-back position. The 28-year-old's form in an Atletico shirt last term was so good that his omission from Brazil's World Cup squad was met with disbelief in some quarters. Today's full-back has to be equally comfortable in the opposition's half as he is his own - something that causes no problems for Luis.

Last season Chelsea shipped just 27 goals, which was 10 fewer than any other Premier League club. If nothing else, it goes to show where the team's major frailties festered. Captain John Terry in particular received high praise for what many viewed as a footballing renaissance. Prior to Mourinho's arrival, it seemed that the former England skipper was heading for the exit door.

However, at 33 and with a couple of serious injuries under his belt, it remains to be seen just how much longer Terry can continue to churn out the performances required of a centre-back in a team that is challenging for major prizes. He has recently been ably partnered by Gary Cahill, while Branislav Ivanovic and youngster Kurt Zouma can cover.

Even so, Mourinho has made no secret of his admiration for Varane, whom he nurtured for a while at Real Madrid. He may only be 21, but the defender has already played in a Champions League final and the World Cup with France. Standing at 6'3", Varane rarely loses a battle in the air, while on the floor, his quick turn of foot means that he is almost never out-paced.

On reflection, Mourinho would probably admit that he was wrong to throw all of his eggs in the Wayne Rooney basket 12 months ago. His Chelsea squad was in desperate need of a goalscoring injection, but despite a reported trio of bids and Rooney's desire to make the move, Manchester United stood firm.

Consequently, having loaned out Romelu Lukaku to Everton, Mourinho had left himself with a combination of Fernando Torres, Samuel Eto'o and Demba Ba. Between the three of them, they scored just 19 Premier League goals, while Lukaku scored 15 on his own at Goodison Park.

The arrival of Costa, assuming that he can continue last season's form in front of goal, will give Chelsea a much greater attacking threat, but the alternative options must also improve. Eto'o's contract has expired, while offers are thought to be welcome for Ba. As for Torres, he's had more than enough chances to prove himself and must now be regarded as an expensive flop.

While Hernandez is not the greatest footballer to have ever graced the Premier League, he is at least a proven scorer of goals. His movement and speed will attract the attention of defenders, which in turn would give Chelsea's more creative players extra space to roam. If he can be convinced to swap Man United's bench for Chelsea's, the Mexican would be a cheap yet useful addition.