The 37-year-old Italian, one of United's inaugural marquee signings, will remain at United until the end of the 2022-23 campaign.

"I'm very happy because me and the club, we wanted the same thing so it was very easy," Diamanti told reporters on Friday.

"I'm excited to continue to try to help this club to grow fast and quick because we want this and we want to try to win something this year."

Diamanti scored five goals in 17 games at United before the season was suspended, with his creativity on show throughout.

"It's huge news for us as a football club - it's huge news for the whole A-League as well," United coach Mark Rudan told reporters on Friday.

"Alessandro came here as a marquee and I believe he is a marquee in every sense of the word - not just what he's done on the field but also off the field as well."

Diamanti stayed in Australia during the season suspension and said he was focused on making and having an impact in the finals.

United sit in sixth place on the table with six games left in the regular season.

"I'm staying here because I want to finish the season, I want to finish my business," Diamanti said.

"We want to finish the season (and) we want to finish well.

Our goal is the finals ... we worked very hard in the (shutdown) period and when we came back here, we worked very hard with a very good attitude.

" ... I'm very happy because the guys believe. We want to try to do something special."

Australian Associated Press