Chelsea can qualify for the knockout stages of the Champions League with victory on Wednesday night.
Although the margin of victory is important.
Frank Lampard's men can make it through to the last 16 of the tournament with a game to spare if they beat their Spanish hosts by two goals.
Qualification for the knockout phase is done on the head-to-head record between teams in the group if two sides are locked on the same number of points.
And with Chelsea, Valencia and Ajax all locked on seven points each, it's a tight finish to the group.
The Blues lost the first game against Valencia 1-0 at Stamford Bridge, meaning a win by two goals against the Spanish outfit at the Mestalla will secure their passage into the last 16.
And Lampard will want to have as strong a squad as possible available for the match.
He has been boosted in that regard, with the news that one of his injured players is back fit and ready for selection.
England international Ross Barkley has been missing since the 1-0 win against Newcastle United in October after picking up an ankle injury.
He was initially called up to Gareth Southgate's squad for the international fixtures against Montenegro and Kosovo over the international break, but had to withdraw as a result of the problem and then missed out against Manchester City on Saturday.
However, the 25-year-old is back in training and ready to stake his claim for a place in the starting XI against Valencia in the Champions League.
As is always the case with UEFA competitions, the media are allowed to watch a portion of open training ahead of matches and Barkley was seen training with the rest of the squad before the Blues headed out to Spain for the match.
