Throughout the season former player Clive Walker provides radio and TV commentary on Chelsea's games. Here he selects five aspects from Saturday's derby victory that caught his eye.

We have a packed schedule in December so we have to accept that some games are going to be a grind, whether that's against a team at the top of the league or the bottom of the league. In a busy period players get mentally and physically tired and it's tough for Jose Mourinho to keep rotating players but still keeping them at their freshest. We'll take the victory and move on.

A Crystal Palace side from six weeks ago probably wouldn't have come back as they did, and they wouldn't have been as good as they were in the second half. When Marouane Chamakh pushed forward to help Cameron Jerome later in the game they looked better, and you could tell Tony Pulis used his experience when delivering his half-time team talk.

Willian played in the middle of the three behind the striker and he was terrific. He's still getting used to the Premier League but it looked like he suited the number 10 role because he could get more involved in the play. His work-rate was unbelievable and I'm looking forward to seeing him play at that level again.

That meant Juan Mata was out wide on the right, where we have seen him play before, and he found space to operate in, particularly in the first half. We want him to be delivering balls through players and over the top of players into box, and when he finds that kind of space it has to be good for us.

Michael Essien played really well, particularly after the disappointment of his last game against Southampton, when he was replaced at half-time. His contribution in that holding role was terrific, he was well-disciplined and he helped keep the shape of the team.

Clive Walker is part of the commentary team for games on this season. Go to our Matchday Live section or hear it via our Mobile App.