Edinson Cavani signing a contract extension at Manchester United last summer was considered one of the best moves of the window.
The Uruguayan had a blistering end to his debut season at Old Trafford with 10 goals in his last eleven games, scoring three times against Roma in United's Europa League semi-final tie, as well as netting in the final in a losing effort over Villarreal.
Cavani showed no signs of slowing down at the age of 34 as he helped Ole Gunnar Solskjaer's side secure a runner-up finish in the Premier League.
There were claims he was considering offers from South America and various other clubs as contract talks stalled throughout the season.
United were delighted to keep him for another season, as a result, and he was primed to have another big year at the club.
But things haven't quite gone according to plan - something that has been a common theme throughout United's season.
There are not many players whose form has dipped so drastically from one year to the next.
Cristiano Ronaldo's arrival certainly disrupted proceedings as Solskjaer had to quickly alter his plans to accommodate the Portugal international.
Cavani was the fall guy as Ronaldo immediately took his place in the starting XI with no sign of him regaining it given the forward's electric start to his second spell at Old Trafford.
Cavani was given chances, albeit sporadically, but the momentum he gained from the end of last season had vanished and he didn't score in his first nine appearances for the Red Devils.
Not many strikers score 10 in eleven to end a campaign but don't get a sniff the following season. That's the Ronaldo effect for you.
There were signs they could form a partnership, however, when Solskjaer decided to go two up front away at Tottenham in a 3-0 win, which led to the sacking of Nuno Espirito Santo.
It wasn't the most exciting football to watch, but it was effective as the strikers linked up seamlessly with both getting on the scoresheet.
That could have been something to build on but that's when injury issues came into the equation for Cavani. He missed 10 games over the course of two months as Solskjaer was axed and Ralf Rangnick took over on an interim basis.
Cavani netted on his return against Newcastle but has failed to get on the scoresheet since with limited game-time, before picking up another injury that still has him on the sidelines.
There are certainly questions marks surrounding his current health, however, as he trained for three days before the Manchester derby but still didn't make the squad that were dismantled by their city rivals at the Etihad on Sunday as Manchester City ran out 4-1 winners.
United definitely could have utilised Cavani with Cristiano Ronaldo out injured as Rangnick opted to use Bruno Fernandes as a 'false nine', something that dramatically backfired.
Roy Keane reckons something "didn't add up" with Ronaldo's injury and the same could be said about Cavani, given the fact he returned to training prior to derby day.
Rangnick revealed that Cavani ruled himself out of the game as he expressed his frustration about the situation.
The interim boss refused to say if the 35-year-old picks and chooses when he is available but certainly suggested that was the case by saying he couldn't force him to play.
The interim boss said: "Edi trained well in the last three days but, in the end, he didn't feel quite well enough to be able to play.
"What does it help if I tell you it's frustrating? It's just a fact if players tell the doctor and the medical department that they are injured and cannot play. I have to accept it as a manager."
Asked if Cavani decides when he plays, Rangnick continued: "Edi trained in the last three days, he trained well, but he still felt after those three training sessions that he is still not fit to play.
"This is a fact and as a manager, I cannot force a player to play if he doesn't feel fit or well enough to play.
"I cannot force a player to play if he thinks he's not available because he has an injury."
There have been continuous reports of disharmony in the dressing room and it's fair to assume Cavani is one of the disgruntled players given the fact he has barely kicked a ball this season, especially given his form last term.
It's not a secret that the Uruguay international will move on this summer so who would blame him if he couldn't find the motivation to put his body on the line for United on Sunday if he wasn't fully fit.
