Diego Costa is set for his return to the pitch in Chelsea's upcoming Champions League tie against Paris Saint-Germain.
Indeed, ever since his untimely ban, Chelsea haven't quite looked the same, with some minor problems being witnessed even before Costa's departure.
But, along with the return of Cesc Fabregas from a hamstring strain, Mourinho will be hoping Costa's return will go some way to changing Chelsea's goalscoring problems seen in recent weeks.
Diego Costa has been a huge force in the forward line for the Blues this season, netting 17 goals in 19 Premier League fixtures. His strength and ability to frustrate defenders has made him a talisman for the Blues' continued success this season.
Even when Chelsea fail to perform, you can expect Costa to put 100% of his work into making something happen, as seen against Liverpool in the League Cup.
Despite scoring 17 goals this season, Costa has not scored for for Jose Mourinho's side in the Champions League. He's come close versus Schalke and Maribor, where he scored a wrongly disallowed goal, but he is yet to score in five Champions League appearances for the Blues.
Where better to score than in Paris, the home of Chelsea's quarter-final opponents in the 2013-2014 season. Coming up against world-class forwards including Zlatan Ibrahimovic and Ezequiel Lavezzi, the Blues need to be able to respond with goals of their own.
Costa will fight for this, whether the rest of his teammates perform or not. Chelsea have become over-reliant on Costa for good reason; they know exactly what he's capable of.
Scoring against the Ligue 1 champions is definitely not impractical for a player of Costa's ilk. In fact, expect to see entertainment in what promises to be a dramatic tie.