Two clubs coming off victories in their last matches will collide in Week 2 of the Union of European Football Associations (UEFA) Champions League when Barcelona host Bayer Leverkusen today at the Nou Camp. 

Defending champions Barca have played three La Liga matches heading to the match against Leverkusen and are 2–1 in those previous outings. 

The biggest news for the Catalans is the loss of club star Lionel Messi who was injured in their victory over Las Palmas in La Liga play. 

Messi tore a ligament in his left knee and is expected to miss two months of action for Barcelona. 

Expected to fill in the void left by the Argentine is the 20-year-old  Munir El Haddadi who will be playing alongside Neymar and Luis Suarez if he will be used against Leverkusen.

 Despite having a young talent possibly stepping up, Barcelona manager Luis Enrique said, according to BBC Sport, that Messi is irreplaceable. 

But it is not all bad news for the hosts as Sports Mole reported that midfielder Andrés Iniesta and defender Dani Alves might be returning from injury against Leverkusen today. 

Barcelona began their Champions League title defense with a 1–1 draw against AS Roma and are currently tied with the club with one point in Group E. 

Meanwhile, Leverkusen are on a two-match winning streak in the Bundesliga heading to their match against Barcelona. 

Unlike Tuesday's opponents, Leverkusen started their Champions League with a win beating BATE Borisov 4–1 to take the top spot in Group E with three points. 

The player to watch out for Leverkusen is midfielder Hakan Çalhanoğlu who will look to repeat his performance against BATE where he had a brace. 

Despite Messi not joining Barca, Leverkusen's defense should still be ready for all the offensive threats that Enrique has like Neymar and Suarez. 

The match between Barcelona and Bayer Leverkusen will be today, Sept. 29, at 2:45 p.m. EST. To watch via live stream, click here.