The Champions League group stage concludes this week with a host of issues still to be resolved.

Barely a third of the 32 teams know exactly what position they will finish in, with eight places in the round of 16 yet to be claimed and a handful of sides still hoping to secure Europa League berths.

Here, the PA news agency considers five things to look out for in the final round of group fixtures.

Red alert

No reigning champion has failed to get through the group stage since Chelsea in 2012 but Liverpool are at risk of following in the footsteps of their Premier League rivals. Jurgen Klopp's holders go into the final round sitting top of Group E but knowing a defeat away to free-scoring Red Bull Salzburg would likely see them finish outside the top two, with the Austrian side and Napoli – who host rock-bottom Genk – going through instead.

Ronaldo records under threat

Cristiano Ronaldo is the only player in Champions League history to have scored in every group match in the same season, but he may soon have to share that record with Bayern Munich's Robert Lewandowski and Erling Braut Haaland of Salzburg. The duo have been in stunning form this season, netting over 50 times between them for club and country, and one more goal for either this week would see them equal Ronaldo's mark. Lewandowski, who struck four against Red Star Belgrade in the previous round, is also just one goal behind Ronaldo's all-time group record of 11. The Pole could now make history when Bayern, looking to become only the seventh team ever to win all six group matches, host Tottenham on Wednesday.

All hail Haaland

Irrespective of what damage he might do to the personal interests of Liverpool and Ronaldo this week, Haaland will not forget the past few months in a hurry.  The 19-year-old Norway striker has scored 28 goals in just 21 appearances for Salzburg this season, including five hat-tricks and eight goals in the Champions League. Unsurprisingly that has seen him linked with some of the game's biggest clubs, and he could add a few more suitors to his collection – and euros to his price tag – against the holders on Tuesday.

Chelsea blues?

Chelsea, Ajax and Valencia are all past Champions League finalists but one of those clubs will be bidding farewell to the competition on Tuesday night. Ajax are in pole position in Group H, sitting two points clear of their rivals and needing only a draw at home to second-placed Valencia to be certain of progressing. Chelsea have some work to do, however. Frank Lampard's men are currently third, behind the Spanish side on head-to-head record, and know anything other than a home victory over eliminated Lille could see them consigned to the Europa League.

Adios Atletico and arrivederci Inter?

Several other members of European football's aristocracy are also at risk of missing out on qualification to the last 16. Atletico Madrid, runners-up in 2014 and 2016, are battling Bayer Leverkusen for second place behind Juventus in Group D, while one of Inter Milan or Borussia Dortmund will also bow out. Serie A leaders Inter are above the Germans due to a better head-to-head record but they must face Group F top dogs Barcelona in their final match while Dortmund take on winless Slavia Prague.