Jose Mourinho has called on his Chelsea reserves to prove their worth as the Blues continue their hectic December schedule with a trip to Sunderland in the League Cup quarter-finals. Mourinho's side closed the gap on Premier League leaders Arsenal to two points with a 2-1 win over Crystal Palace, but with a crunch clash against the Gunners looming on 23 December, Mourinho is likely to rest several of his stars for the clash at Sunderland on Tuesday. Centre-half Gary Cahill was rested at the weekend as a precaution following a minor thigh problem, and could return to the defence alongside David Luiz as Mourinho would like to rest captain John Terry. Branislav Ivanovic is suspended, so Cesar Azpilicueta will switch to his favoured right-back role, with Ashley Cole returning on the left. "Now is an important period for all of the squad - everyone has a role to play and a contribution to give," Mourinho said. "Every player will be important when we have so many games and competitions to play. "Azpilicueta can go on the right, Ashley Cole on the left, with David (Luiz) as a central defender. "If Cahill recovers, I will play him if he does not recover, then I will go again with John, but I would like to give John a rest for that match." Mourinho also admitted he has been impressed with Terry, who has been in good form since coming back into the side this season after losing his place under interim boss Rafael Benitez last term. "He is very solid, very focused with the ball he makes the right choice, and without the ball he is also very focused," Mourinho added. "I think he is having a very good season, let's see if he can keep going this way because he has been fantastic." Source: FIFA.com