WATCH: Messi scores wonder goal, pays tribute to Maradona
Messi scored in fine style to cap a 4-0 victory over Osasuna at Camp Nou on Monday (AEDT), a game that was preceded by a tribute to former Barca star Maradona, who died on Thursday.
Having found the net, Messi removed his Barca shirt to reveal a Newell's Old Boys jersey bearing Maradona's famous number 10. The 1986 World Cup winner spent a season at the club, where Messi was later a youth player, towards the end of his career.
Koeman was impressed both with his captain's finish and with the way he chose to pay his respects to his Argentine compatriot.
"These are the things of a great player: first because of the play and the goal, and second because of the gesture towards Maradona. It was something really great in every sense," Koeman said.
"I didn't know Leo was going to do that celebration."
Antoine Griezmann was arguably Barca's star performer against Osasuna, assisting Philippe Coutinho's goal after having scored a stunning volley three minutes before half-time.
The France international at last appears to be finding his feet for the Catalans, having been directly involved in six goals in his past six matches after contributing to just one in the previous 20.
"Antoine looked very good today," said Koeman. "From his position, he played with a lot of freedom, he gave an assist and scored a great goal. This is the player we want.
"I don't think he has changed. He always worked hard to have this opportunity, but he scored a great goal and now it seems he feels freer on the pitch and that's a positive."
The opening goal was scored by Martin Braithwaite, who has scored in consecutive matches for the first time since January for Leganes and has contributed three goals and one assist in his most recent four games.
"We needed more of a number nine today to fix the centre-backs and to be able to find more space behind a team that closes up at the back," Koeman said.
"Martin is working very well. We know the team works well in defence, they played with five at the back, and we had to play with a high rhythm with the ball to look for goal."
The only sour note for Barca was the loss of defender Clement Lenglet to what looked like an ankle problem, with Koeman having already seen Gerard Pique, Samuel Umtiti and Ronald Araujo succumb to injuries.
However, the coach hopes his remaining senior centre-back has not suffered anything serious.
"I have spoken with the doctor and it seems we will have to wait for tomorrow for tests, but it does not seem that serious," Koeman said.
"I don't know about Wednesday's game [against Ferencvaros in the Champions League] but I hope it's nothing major."
