WATCH: Sergio Aguero Marks New Deal With Goal as Man City Routs Cardiff

Sergio Aguero celebrated signing a new contract with Manchester City by scoring the opening goal in a 5-0 win over Cardiff in the English Premier League on Saturday.

CARDIFF, Wales (AP) Sergio Aguero celebrated signing a new contract with Manchester City by scoring the opening goal in a 5-0 win over Cardiff in the English Premier League on Saturday.

The Argentina striker's fourth league goal of the season came on his 300th appearance for City, which bounced back from its surprise midweek loss to Lyon in the Champions League.

Bernardo Silva, Ikay Gundogan and Riyad Mahrez - with two second-half goals as a substitute - also scored at Cardiff City Stadium as City recorded a fifth win in the opening six games of its title defense.

City announced on Friday that Aguero penned a one-year extension to his contract, tying him to the club until 2021 and likely meaning he'll see out a decade at Etihad Stadium.

The fans' favorite was back in the starting lineup after getting dropped to the bench against Lyon and was dangerous throughout, getting his goal in the 32nd by finishing off a squared ball by Bernardo.

The Portugal playmaker turned scorer three minutes later when he flicked in a cross from Leroy Sane.

Gundogan curled in a classy third just before halftime after exchanging passes with Raheem Sterling, before Mahrez scored in the 67th - with his first since joining in the offseason from Leicester - soon after replacing Aguero and again in the 89th.

No. 1 for Mahrez (📹:@NBCSportsSoccer) pic.twitter.com/9BhqQJqA3q

— SI Soccer (@si_soccer) September 22, 2018

Man City faces Oxford United in the third round of the League Cup on Tuesday.