After a three-month break, the UEFA Champions League resumes this week with four Round of 16 first legs taking place across Europe.

Defending UCL holders Liverpool visit La Liga side Atletico Madrid on Tuesday looking to extend its 14-match unbeaten run in all competitions. Jurgen Klopp’s squad continued their runaway of the Premier League title with a 1-0 road win over Norwich City as Sadio Mane bagged his 15th goal in all competitions. The Senegalese forward will headline a stacked Liverpool attack on the road.

Elsewhere, Borussia Dortmund welcomes Ligue 1 giants Paris Saint-Germain to Signal Iduna Park also on Tuesday. Tottenham welcomes RB Leipzig to London on Wednesday while Atalanta and Valencia also square off on the same night.

Here’s a closer look at this week’s Champions League action:

Atletico Madrid vs. Liverpool

Tuesday, 3 p.m. TNT, B/R Live, Univision

Injuries of Note: Keiran Trippier, Diego Costa, and Joao Felix are all out for Atletico Madrid following their 2-2 draw with Valencia on Friday. Liverpool will be without Xherdan Shaqiri and Nathaniel Clyne but have numerous players returning like James Milner and Joe Gomez.

Key to the Game: Atletico Madrid are known for their stubborn defensive tactics, but will need to limit the wing play of Liverpool for a chance at a home win. Liverpool will try to press Atletico high up the field in order to force turnovers and use the skill of Mane and Mo Salah to create goalscoring opportunities.

Player to Watch: Sadio Mane’s ability to score in big games has been crucial for Liverpool this season and the forward will need a strong outing to give the Reds a positive result prior to their return to Anfield.

Borussia Dortmund vs. Paris Saint-Germain

Tuesday, 3 p.m. B/R Live, Univision

Injuries of Note: Marco Reus, Thomas Delaney, and Julian Brandt are all out for the first clash in Germany for the hosts. PSG are likely to have Neymar available for the first leg, but full back Juan Bernat is out.

Key to the Game: Both teams can score plenty of goals when needed, but possession will be key at Signal Iduna Park for both teams. Dortmund will try to slow down the game and work possession around for the best scoring opportunities. PSG with the likes of Kylian Mbappe and Neymar will be aiming to put the tie out of reach away from home.

Player to Watch: Mats Hummels was part of Dortmund’s roster the last time these teams met in the Champions League under then manager Jurgen Klopp. Hummels will lead the Dortmund backline against one of Europe’s top attacks and will need to lead a compact defensive unit to keep PSG off the scoresheet.

Tottenham vs. RB Leipzig

Wednesday, 3 p.m. TNT, B/R Live, Univision

Injuries of Note: Tyler Adams was likely to make his Champions League debut for RB Leipzig, but has been ruled out for at least the first leg. Tottenham have no major injury concerns for their home fixture.

Key to the Game: Tottenham will rely on the skill and creativity of Son Heung-Min and Dele Alli in attack with Harry Kane still sidelined. Both players could give the Leipzig backline fits with their versatility in attack. A lot of Leipzig’s scoring chances come from forward Timo Werner and expect the German to see plenty of the ball in London.

Player to Watch: Werner has 23 goals between Bundesliga and Champions League play and will be eager to add to that total against Tottenham. His physical play paired with his touch in front of goal makes him one of the top forward in the world.

Atalanta vs. Valencia 

Wednesday, 3 p.m. B/R Live, Univision

Injuries of Note: Atalanta only has defender Bosko Sutalo as a doubt for the game on Wednesday evening. As for Valencia, defender Gabriel is suspended while Ezequiel Garay is unlikely to feature.

Key to the Game: Both teams will look for a strong first leg performance to set the tone for possible advancement to the quarterfinals. Atalanta will look to use the creativity of Alejandro Gomez and Marten de Roon to set up the likes of Duvan Zapata and Josip Ilicic. Valencia has offensive firepower of their own with Maxi Gomez and Rodrigo as the headliners.

Player to Watch: Ilicic is one of the underrated forwards in Europe with 14 Serie A goals in 20 appearances this season. However, the Slovenian has yet to score in the Champions League this term and will be eager to do so against a stingy Valencia defense.