Alonso has faith in his team-mates however, and is sure they will still progress past Leverkusen: "I am very confident we'll get the right result. I know some important and key players aren't available for the game but we still have enough good players to beat Bayer Leverkusen. If we can get a good result at home then it will be easier for us in the second leg.
"I see no reason why we can't enjoy a really good Champions League campaign this year. We can definitely get past Leverkusen and after that who knows what can happen?" he added.
"Of course from my point of view I'm very upset at missing this game. It's a very big match for the club and to have to watch from the stands is going to be very hard. I know I'll be feeling very nervous and yet there'll be nothing I can do about what's going on on the field. I'll just have to try and stay as calm as possible, but it's never easy."