The UEFA Champions League Round of 16 second legs conclude this week with eight teams fighting for the final four places in next month’s quarterfinals.

Juventus, Liverpool, Manchester City, and Real Madrid have already booked their places in the quarterfinals and will now wait to see who else will join them.

After a 1-1 draw in their first meeting at Stamford Bridge, Barcelona and Chelsea square off at the Camp Nou on Wednesday with the hosts holding the away goals tiebreaker. Elsewhere this week, Manchester United faces Sevilla at Old Trafford while AS Roma faces Shakhtar Donetsk at home. Bayern Munich travels to Besiktas also on Wednesday, holding a huge aggregate lead.

Here’s a closer look at this week’s UCL action:

MANCHESTER UNITED VS. SEVILLA (Tuesday, 3:45 p.m., Fox Sports 1, ESPN Deportes. Teams tied 0-0 on aggregate.)

Injuries of Note: Anthony Martial and Paul Pogba are doubts for United, while defenders Marcos Rojo and Daley Blind and are also expected to miss out. Former Manchester City man, Jesus Navas is expected to miss for Sevilla

Key to the Game: Manchester United sat back and allowed Sevilla possession in the first meeting, but will need to change their tactics at home. Offensively, wing play will be huge for United, who did well in their weekend win vs. Liverpool. Sevilla will have the best chances on counter attacks.

Player to Watch: United keeper David de Gea was huge in the first leg in Spain, making eight saves in a clean sheet. The 27-year-old has been huge in several matches for United this season, and may see his number called on numerous occasions at the Theater of Dreams this week.

Quote:  “Very important for our confidence to win this sort of game,” Manchester United midfielder Nemanja Matic said. “We won against Chelsea and of course (on Saturday), so confidence will be on a high level, for sure.”

AS ROMA VS. SHAKHTAR DONETSK (Tuesday, 3:45 p.m., Fox Sports 2, ESPN3. Shakhtar leads 2-1 on aggregate.)

Injuries of Note: Fullback Rick Karsdoorp and midfielder Lorenzo Pellegrini are out for Roma while Shakhtar’s big loss is the suspended Darijo Srna.

Key to the Game: Shakhtar held their own against the Romans in their first meeting, and will need to prepare for an even tougher match in the second leg. Roma will use the home crowd to their advantage, and will look to own possession. Shakhtar will hope to hit Roma down the flanks and bolster their aggregate lead.

Player to Watch: Turkish midfielder Cenzig Under has had a stellar start to 2018, scoring his only six goals of the season since February. The 20-year-old found the back of the net in the first leg, and has had a huge impact in Roma’s midfield play.

Quote: “It won’t be easy in Italy, but Shakhtar are a good team with experienced players,” Ukraine National Team coach Andriy Shevchenko said. “They should go out at Stadio Olimpico and do a job there. Shakhtar impressed with their fitness. The team improved in the second half despite a three-month winter break. Shakhtar put in a good display overall.”

BESIKTAS VS. BAYERN MUNICH (Wednesday, 1:00 p.m., Fox Sports 2, ESPN3. Bayern leads 5-0 on aggregate.)

Injuries of Note: Corentin Tolisso suffered a bad bruise to his shin during Saturday’s rout of Hamburg and is a major doubt. Manuel Neuer and Kingsley Coman are both long-term absentees for Bayern. James Rodriguez is expected to return for Bayern after missing Saturday’s match. Besiktas defender Domajov Vida is suspended after his red card in the first leg, but in-form Ricardo Quaresma is expected to be available for the Turkish side.

Key to the Game: If Besiktas wants to complete a miraculous comeback then they will need to attack on all fronts. The hosts cannot afford to sit back and allow Bayern the bulk of the chances and possession.

Player to Watch: Quaresma, a Portuguese international has three goals and nine assists this season but is huge to Besiktas’ build-up play. He is a gamechanger and has good skills with the ball at his feet. Besiktas will need him to have an impact for any chance of coming back in the tie.

Quote: “It’s a really good performance and important result ahead of the Besiktas game on Wednesday,” Bayern coach Jupp Heynckes said following Saturday’s rout of Hamburg.

BARCELONA VS. CHELSEA (Wednesday, 3:45 p.m., ESPN3, Fox Sports 1. Teams tied 1-1 on aggregate.)

Injuries of Note: Denis Suarez is expected to miss out for Barcelona, due to an muscle strain in his left leg. Andres Iniesta should return for Barcelona. Meanwhile for Chelsea, David Luiz is still suffering with a knee problem, while Ross Barkley has only appeared three times all season. Tiemoue Bakayoko has not featured for the Blues since being sent off against Watford last month.

Key to the Game: Barcelona should have the bulk of the possession and will look to find the best opportunity to score. Lionel Messi and Luis Suarez will both be chomping at the bit to get after a Chelsea backline who has been up and down this season. Chelsea will need to use their possession to the fullest and frustrate Barcelona when they have the ball.

Player to Watch: After not scoring this weekend, Lionel Messi will look to put his team on his back on Wednesday. The Argentine leads Barcelona in goals (31) and assists (15) this season and has already scored against Chelsea in the first leg.

Quote: “We have to show great resilience,” Chelsea boss Antonio Conte said. “The game for sure will be totally different and we are paying against one of the best teams in the world. We must pay great attention and have the same focus and concentration of the first leg against Barcelona.”