Essien was formerly known as 'The Bison' until Mourinho decided his all-action displays were more reminiscent as an express train than a type of wild cattle.

The Ghana international certainly kept Chelsea on the right track in their quarter-final second leg against Valencia when he scored the last-gasp matchwinner that set up a rematch with the Merseysiders.

It was Essien's first game back in the side following a knee injury sustained in the FA Cup quarter-final draw with Tottenham at Stamford Bridge on March 11 and he capped his comeback with the decisive goal.

But Essien's first-minute booking in the same leg rules him out of the opening game with Liverpool and Mourinho's side know exactly what they will be missing.

Mourinho said: "Essien is a special player. He is an athlete. He can run forever. He could play a game every day. He is a superb athlete. When we lost him one month ago it was a big, big loss.

"But he was ready to come back for the Valencia game. I know he is suspended for the next game but this one was the crucial one. The next one is not crucial."

But Mourinho refused to be drawn on getting revenge against Liverpool for their semi-final defeat two years ago when Luis Garcia's controversial winner was adjudged to have crossed the line.

Mourinho still insists the ball was cleared by William Gallas before it had fully crossed the line but is determined not to hype up the rematch a grudge encounter.

Mourinho added: "Revenge is not for me. It is not a word for me in football or life. We know we start from behind and why - it is simple because Liverpool plays only Champions League, we play everything else.

"We have players suspended and on yellow cards and Liverpool is in a very clean situation so I think they start in front of us.

"But the mentality and the character my players are showing - we will be ready for them."