Without question, one of the most improved players at Manchester City under Pep Guardiola has been Raheem Sterling.
Now in his third season at the Etihad, the winger has proved himself to be a key component of a Guardiola-style team -- his fast pace is crucial on the counter-attack, his positional awareness is a large factor in engineering shooting opportunities for himself and others, and his understanding of his role has also brought the best out of his teammates.
He's looking every bit a bargain at £49 million, a transfer fee that was ridiculed in 2015 when the England international made the switch from Liverpool. Even in the context of how spending has skyrocketed in the years since that deal, no transfer after Sterling's has garnered the same level of criticism.
Looking back at that transfer tussle, it is little surprise that Sterling initially struggled to settle. He was painted as not just the bad guy, but one of the most mercenary footballers to have graced the Premier League -- pundits were queuing up to give their thoughts on why he should have stayed at Liverpool and he was being branded "greedy" or "ungrateful."
As much as he insisted the switch was about furthering his career and aiming to win trophies, it was always painted as being about money. He may have only won one competition at City in his two-and-a-half seasons at the club -- the 2016 League Cup -- but there certainly looks like there'll be more winners' medals in his cabinet over the next few years. And it doesn't look like such a bad decision now.
Throughout his time at City, Sterling has been booed mercilessly at pretty much every away ground he's been to. Many opposition fans say it's down to his poor display at Euro 2016 with England, however the abuse began in that 2015-16 campaign -- 12 months before he underperformed, just like the rest of the England team did, in France.
It didn't go unnoticed, either. Sterling dubbed himself "the hated one" on social media and you can only imagine what that does to the psyche of a man who was just 21 at the time. How could he not be affected if that was what he thought of himself?
But City fans are now revelling in his transformation. Sterling's performances this term have been so good that he's been able to turn around the public perception of him -- there's barely a jeer or whistle when he's on the ball, something that was still going on for much of last season.
Sterling has already scored more goals this campaign (14) than he ever has in an entire season and his longest streak without finding the net is just three games. He's regularly been the difference between City drawing and winning, too -- as crucial goals in 2-1 wins over Bournemouth, Huddersfield and Southampton and the 1-0 success at Newcastle all demonstrate. That's four strikes that have earned City eight points alone.
The winger faces perhaps one of his toughest tests of the season on Sunday, however. It's fair to say that Sterling has never performed well for his new club when facing Liverpool -- yet to truly make an impact in the five games he's played against his former team, including missing two gilt-edged chances to wrap up the 1-1 draw in the League Cup final that his side eventually won on penalties in 2016.
But that was the old, widely-ridiculed Sterling. He was a player that hadn't benefited from 18 months of Guardiola's tutelage and hadn't developed into one of the deadliest attackers in Europe. He was inconsistent, showing flashes of brilliance alongside mistakes and indecision.
For two seasons at City, he was just potential, with only the odd moment of quality when it really mattered.
Now, though, they've got perhaps the Premier League's most exciting attacker. He understands when to cut inside and create space for right-back Kyle Walker to overlap. He can read when he needs to join striker Sergio Aguero in the box to become an added goal threat. He drifts around the front three positions, making himself near impossible to mark. He also finds the net more often than not.
Sterling will be jeered at Anfield -- Liverpool are the only club with any right to make him the pantomime villain -- and how well he is able to cope in that pressure cooker environment will go a long way to deciding how well City do in the game.
Guardiola's side have an abysmal record at Liverpool and if they're to turn that around, then the performance of Sterling could be the difference.