Chelsea manager Frank Lampard argued last week that veteran striker Olivier Giroud is "getting better with age".
The Frenchman proved his point with a stunning performance at the Ramon Sanchez Pizjuan on Wednesday night.
The 34-year-old became the oldest player in Champions League history to score a hat-trick before then converting a penalty, which he had won himself, to put the seal on a sensational 4-0 win that sealed top spot in Group E for the Blues.
Giroud had gone into the game having started just one previous game this season. However, he now has six goals to his name, averaging one every 45.5 minutes.
"It was an amazing performance from Oli, to score four goals at this level, against a really good opponent," Lampard told reporters after the game.
"There was the quality of goals but also his contribution to the team performance, so it was right that he got a standing ovation as he came off the pitch.
"I'm delighted for him because he is the ultimate professional, and I think he's shown that throughout his career. I also think that's why Oli has such great numbers for France and in the Champions League.
"He wasn't always a regular before I got here, but as soon as I came in I could feel the positivity off him as a player, in terms of how he wants to train and how he wants to affect people whether he starts or not.
"So, he's started a lot for us now and been very impactful. He's a great example for younger players, but also guys that don't always start, which happens a lot as we have a squad of 20-plus players."
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Lampard has stated several times that he doesn't want to sell Giroud but the striker has already admitted that he is concerned by his lack of game time ahead of next summer's European Championship. Indeed, he says he will look for a move during the January transfer window if his situation doesn't improve.
It is, however, essential that Chelsea keep Giroud, even if that means losing him for nothing when his contract expires at the end of the season. He won't be short on offers, that's for sure.
Inter were close to signing him during the last winter window but the deal collapsed because the west Londoners couldn't sign a replacement. Lazio and Tottenham were also interested but joining former Blues boss Antonio Conte at San Siro was always his preferred option.
Luckily for Lampard, Giroud ended up staying at Stamford Bridge. The World Cup winner scored seven goals in 12 appearances to help Chelsea qualify for this season's Champions League via a fourth-place finish in the Premier League.
The competition for places has only intensified during the off-season, of course, following the arrivals of Timo Werner, Hakim Ziyech and Kai Havertz. In addition, a revitalised Tammy Abraham has staked his claim for the No.9 role with five goals and four assists.
Giroud, though, has now responded in spectacular fashion, making his case to be Lampard's leading man with an excellent all-round display in Seville.
"When you play Oli, you know what attributes you're getting," the Blues boss explained. "He has great qualities to hold the ball up, obviously, but also to convert the kind of passes that N'Golo Kante plays into the box.
"So, it's important we get a lot of energy around him, people that can run off him and support him. Because then you have a top player playing with quality and dedication."
The importance of Giroud's attitude certainly shouldn't be downplayed. Even in the lead-up to the game against Sevilla, midfielder Jorginho was hailing the forward's influence on his team-mates, who were thrilled when he netted the winner against Rennes last week.
“I am so happy because he deserves it because of the person he is, the way he works every single day, with a smile on his face and giving so much for this team," the Italy international enthused.
"And it's not just what he does on the pitch, but how he is in the changing room as well. When I saw the ball going in [against Rennes], I was so happy and even more happy because it was Oli. Everyone loves him. He is such a nice guy.”
Giroud, though, will always fight his corner, and in the best possible manner.
He has made it clear that he wants more game time at Chelsea and he couldn't have made a more compelling case for inclusion in Sunday's Premier League showdown with Leeds than a perfect hat-trick in the Champions League.
Lampard, then, has a massive call to make. He says it's "a great problem to have". But if Giroud is back on the bench this weekend, it may only strengthen his resolve to leave in January.
After all, he's not only shown why Chelsea still need him. He's also shown why he'd still be an excellent signing for any top European side looking for a centre-forward.
As Giroud is proving, age really is just a number. Holding on to him, then, may be essential for Chelsea – but it certainly won't be easy.