In late October of last year, Christian Pulisic arrived at Turf Moor for Chelsea's game against Burnley with fans still questioning quite why the Blues had spent £58 million ($73m) on the United States winger.
Having arrived from Borussia Dortmund ahead of the 2019-20 campaign, Pulisic had largely been limited to a substitute in west London. Indeed, hadn't started a league game for two months.
By the time the final whistle blew in Lancashire, though, Premier League supporters had a better understanding of why Pulisic had received such rave reviews in Germany.
That performance sparked the most prolific period of Pulisic's career to date, with the U.S. men's national team star eventually netting 11 goals in all competitions to go along with his 10 assists.
Just over a year on, Pulisic and Chelsea return to Turf Moor on Saturday looking for a repeat performance and result.
Like last season, Pulisic is yet to truly showcase his full ability in 2020-21, though this time he is recovering from a hamstring injury suffered in the FA Cup final rather than being slowly introduced into new surroundings.
He forms part of a new-look Chelsea attack that has not yet truly gelled, though it is hoped that he can be the catalyst for bringing the best out of the likes of Timo Werner and Kai Havertz.
The early signs are good, with Wednesday's 4-0 win over Krasnodar in the Champions League the surest sign yet that Pulisic can be the key to unlocking the enormous potential within the club's new forward line.
Entering the game with Frank Lampard's side just about holding on to a 1-0 lead, Pulisic proceeded to run a tiring defence ragged, playing a part in all three of the Blues' late goals.
Just seconds after stepping up from the bench, he volleyed the ball into Alyaksandr Martynovich's arm to win a penalty that Werner smashed home.
He then took up possession and drove up field before playing in Werner, who in turn set up Hakim Ziyech for his first Chelsea goal.
Pulisic then rounded off the scoring himself, leaving ex-Chelsea midfielder Joe Cole thrilled by his return to the first-team fold.
"This lad’s a real talent," Cole told BT Sport post-match. "It was a big miss not having him at the start of the season.
"I would argue he’s one of the most important players in Chelsea’s attacking third because he can do everything. He can dribble, run without the ball, he gets in and scores goals. Frank will be delighted."
For Pulisic to be receiving such praise would have been unheard of 12 months ago.
Lampard's decision to largely hold him back was understood by some as a sign that the former England international was unsure whether Pulisic was good enough for a club of Chelsea's stature.
Even Jesse Marsch, the highly-regarded American coach of Red Bull Salzburg, believed that to be the case following a conversation with Lampard during pre-season that left him a little concerned regarding the Blues boss' plans for his big-money addition.
"When I spoke to him [Lampard] in pre-season a year ago now, I was talking to him about having Christian Pulisic," Marsch told Extratime Radio in a recent interview, "and he was kind of like, 'Yeah, he's got a lot to learn so we'll see how he does.'
"I said to him, 'Listen, he was at Dortmund, and they had a high level of tactical thinking, of playing, and he was very successful.'
"He was considered one of the best young players in Germany and that's in a group of players with Timo Werner, Kai Havertz, Joshua Kimmich and these kinds of players.
"And it wasn't just because he was talented but it was because he understood the tactics and understood how to fit in the game, and he was developing a really astute way of playing.
"I could see right away that Frank Lampard's idea of Christian Pulisic was shaped a lot by the fact that he was American and not that his football education came a lot from what has happened in Germany."
Lampard refutes Marsch's assumption, and told a press conference on Thursday that he had "always rated Pulisic" while also explaining, in response to a question from Goal, why he initially held the wideman back.
"I coached in the Premier League and played in it for nearly 20 years. I understand the rigours of it," he said. "That brings me on to Christian's development last year. It's clearly the toughest league to come and play as a young player.
"It's not just Christian – some of the greatest players in Premier League history, whether they came from America or Europe, showed that.
"What Christian did was find his feet very quickly and have a breakthrough season in the Premier League where he produced more goals and assists than he had produced [previously].
"His performances last year were massively impressive on his own, but he will get better and better because he is a young player. I never doubted him in the first place."
Lampard's increased faith in Pulisic following his Burnley hat-trick was certainly not misplaced, though it was until after the Premier League's enforced break in the spring that the American began to deliver on a consistent basis.
Pulisic had a direct hand in nine goals in just 11 games post-lockdown to help Chelsea reach the cup final as well as secure Champions League football with a top-four finish.
So strong were Pulisic's performances that some were suggesting he was reaching the levels of the man he was signed to replace, Eden Hazard, and if he can maintain that form now he is back up to full speed, then Chelsea's attack could be about to truly take off.
Lampard still has to sort out the best configuration for his masses of forward talent, but one thing is clear: Pulisic is going to have a key role to play.