Harry Redknapp believes Jermain Defoe is reaping the benefit of extra conditioning work this year.
The striker became only the fourth player in the club's history and only the third in the Premier League to grab five goals in a game in Sunday's memorable 9-1 win against Wigan.
'JD' put in extra hours in the gym when he was injured last season and continued to work on that side of his fitness in pre-season.
The England hitman has spoken himself about how he feels stronger than ever this season and boss Harry pinpointed that part of his game when asked how he'd developed.
"He's got stronger," said Harry. "He's using his strength a bit more, holding people off.
"He did some fitness work with the coaches here and he uses his upper body strength more. He's certainly not lightweight any more.
"Jermain is an amazing finisher. He's so sharp around the box, you give him half-a-chance and he makes a yard and bangs it in the back of the net.
"The goals he scored at Hull (a hat-trick earlier in the season) were incredible and he's been doing that since he was 14 - I took him at West Ham at 15 and he was a goalscoring machine."
Harry described Jermain's finishing as 'fantastic' on Sunday. His five goals took him to the top of the goalscoring charts in the Barclays Premier League with 11 goals, just ahead of Fernando Torres, Darren Bent and Didier Drogba.
"I don't see why he can't be the top scorer in the Premier League this season," added Harry. "He's been so sharp in training. You could see this coming."