Barcelona host Chelsea in a pivotal match for both sides on Wednesday night, as the home side look for a first title since 2015 with the domestic title all but wrapped up.
Chelsea see winning the Champions League as potentially their only route back into the competition next season, currently lying four points behind fourth-placed Spurs. With the title long gone and an FA Cup quarter-final to come, Antonio Conte's men will look to grasp this chance for a brilliant upset.
Here are 4 key battles that could decide Wednesday's match:
4. Andres Iniesta vs N'Golo Kante
The veteran Spaniard is on the hunt for his fifth UEFA Champions League triumph, and will have to get past N'Golo Kante to be effective on Wednesday. Iniesta has returned to training after an injury and should play some part in the game.
The Frenchman is the best defensive midfielder in the world on his day, but has yet to be properly tested against a team of Barcelona's calibre.
He coped admirably in the first leg, with one small error allowing Iniesta in to set up Messi for the equaliser. If he successfully keeps Iniesta & co. out at the Nou Camp, Chelsea have a fighting chance of a result.
3. Gerard Pique vs Eden Hazard
As is the case with most Chelsea matches, the Blues' number ten holds the key to their ultimate success, with the ability to turn the game.
If deployed as a central striker like he was in the home leg, Hazard will fancy his chances of besting Pique who, whilst no slouch, is no match for the trickery and invention of the Belgian.
2. Jordi Alba vs Willian
Willian, as he so often does, has stepped up in recent weeks when Chelsea have needed him most, scoring in vital games against the Catalans and Manchester United, amongst others.
The Brazilian has been carrying the team and will relish his first trip to the Nou Camp, where he will run into arguably the best pure full-back in the world in Jordi Alba.
Alba has blistering speed and is deceptively good at tracking back, meaning Willian will have few, if any chances to get behind the Barca back line.
1. Lionel Messi vs Andreas Christensen
After keeping the brilliant Argentine at bay for over an hour in the first leg, Christensen made what proved to be the fatal mistake with an errant ball across the box which the Blaugrana talisman duly converted.
The Dane has made the odd error in recent weeks, still adapting to top-level football in his first season back at Chelsea.
He will hope to avenge his mistake against the world's best, and shut out the Barca double whammy of Messi and Suarez on Wednesday. If they are allowed to roam freely, the Blues have next to no chance of a positive result.