Ronald Koeman has warned Barcelona's rivals a rejuvenated and focused Lionel Messi will have a massive impact in the forthcoming season.

Messi is technically still a free agent after his contract with the Blaugrana expired at midnight on June 30, but it has been widely reported the 34-year-old is poised to sign a new five-year deal at Camp Nou.

Messi was again hugely influential for Barcelona last season, finishing as LaLiga's top scorer and managing 38 goals and 12 assists across all competitions.

He also created 117 chances for others and netted a goal every 110.32 minutes over the course of 2020-21. 

The Argentina international is expected to take a substantial pay cut to stay at Barca but Koeman does not expect his influence to diminish.

"Messi is very important, he is the captain of the team and an example," head coach Koeman told a media conference on Sunday.

"After a difficult start due to his own situation, his effectiveness was enormous [in 2020-21].

"He really wanted to win the Copa America and, as he is the best player in the world, he is used to winning things. For me, he is the big favourite to win the Ballon d'Or."

Koeman claimed the presence of Messi and other experienced players will bring balance to Barca in the new campaign.

"The veteran players have a place in the squad," Koeman explained.

"They already showed it last year and it is important that they be with us. In a club like Barca, the balance between the oldest and the youngest must exist."

Koeman has taken some of the attacking burden of Messi shoulders with the signings of Memphis Depay and Sergio Aguero on free transfers.

Depay enjoyed a fine final season in Ligue 1, scoring 20 times, trailing only Paris Saint-Germain star Kylian Mbappe (27), while his 12 assists and 94 chances created were the most in France's top flight.

Aguero scored a club-record 260 goals in 389 appearances in all competitions during a glittering decade with Manchester City.

"I know Memphis very well and he knows how to work," Koeman added.

"He has a lot of character, physicality, speed, he can play in different positions in attack. He's the perfect age to show it.

"With Sergio, we had to improve our performance at the top and he is a very experienced and dangerous player in the penalty area. 

"The important thing is that he is physically well and our goal is to keep him in top form."