Hansi Flick lauded goal-getter Robert Lewandowski after the striker netted the winner in Barcelona's 2-1 win against Athletic Club at the Olympic Stadium on Saturday.
Lewandowski celebrated turning 36 this week by following up last weekend's brace against Valencia with his third goal in two LaLiga games.
Flick, who worked with Lewandowski at Bayern Munich, has been especially impressed with his fitness and work off the ball.
"I know him, I have worked with him and he's 100% fit, you can see it," the German coach said in a news conference.
"Against the ball he's doing great. He presses with the team from the front, so we always receive the ball very high. It's good for our game.
"Robert is an absolute professional player, working hard on his fitness, this body he has, it's not this age.
"For me, when he is fit, when he is positive, it helps us a lot. He knows how to score goals and also when he is under pressure."
Barça took the lead through Lamine Yamal but Athletic levelled before the break via an Oihan Sancet penalty.
Lewandowski twice hit the woodwork and saw another shot saved brilliantly by Álex Padilla before turning home the winner in the 75th minute.
"We needed this second goal and Robert had the chance and he took it," Flick added.
"This is his job and he is doing this great over years now, not only this year.
"Of course, in the first half especially he could score one or two goals, but I have to see it again, it's just the impression on the bench.
"But, at the end, this is a goal-getter, a striker who scores goals. The second goal for us was the winner, three points, perfect."
Lewandowski's goal ensured Flick's perfect start as Barça coach continued as they made it six points from two games.
"I think it's always good to improve," Flick said of his team's start to the campaign.
"That is what I said to the team. Every match is a step in front, so we want to do better, this is what we are doing.
"We analyse the match, see where we can do things better for the next match."
Barça's start has been all the more impressive given the youngsters involved in the team, with Yamal, Pau Cubarsí and Marc Bernal all still 17.
Bernal made his debut against Valencia at the base of the midfield and kept his place against Athletic.
"It's nothing to do with age, it's to do with performance," Flick said of the young midfielder.
"He's doing good, in the preseason we could say he has something we need. Today also he is doing great and it was not easy against Athletic, they have a good idea how they want to play football.
"It was very important we have a No .6 focused on the defence and this is what he did."