The Champions League returns this week with Manchester United and Tottenham in action along with holders Real Madrid.

Here, Press Association Sport takes a look at some of the main talking points.

Ole up against it

Manchester United's task against Paris St Germain is set to be made
all the more difficult by up to 10 absentees. Unbeaten on the domestic front since Ole Gunnar Solskjaer took caretaker charge in December, the only blot on the interim manager's copybook is last month's 2-0 first-leg loss to the Ligue 1 champions at Old Trafford. France's World Cup-winning midfielder Paul Pogba is banned while United's lengthy injury list is set to include Anthony Martial due to a groin complaint. Nevertheless, Solskjaer has pledged to fight at PSG and try to secure a famous away win akin to the semi-final triumph that saw Juventus beaten 3-2 on the way to the treble in 1999. "If we get an early goal, then suddenly we are in with a shout," he said.

Spurs in good shape

Nicolo Zaniolo emerged as the latest whizzkid on the European  scene after his two goals gave Roma the edge over Porto in the first leg. The 19-year-old, one of the few bright spots in a disappointing season for Roma, opened the scoring when he controlled Edin Dzeko's pass before drilling a low effort past Iker Casillas. He added a second from six yards out after Dzeko's shot came back off a post. But Porto gave themselves a chance with an away goal from Adrian Lopez to make it all to play for at the Estadio do Dragao.

VAR from perfect

Video Assistant Referees were introduced into the competition for
the knockout stages and quickly sparked debate following the contentious decision to disallow an Ajax goal against Real in the first leg. There initially appeared to be little wrong with Nicolas Tagliafico's header until Dusan Tadic – who was in front of Real goalkeeper Thibaut Courtois but did not touch the ball – was shown to be fractionally offside and adjudged to be interfering with play. Prepare for another round of tedious debate about a system that was supposed to put an end to controversial decisions but instead seems to create more.