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The Brazilian was criticised in midweek for his behaviour after Liverpool's Conor Bradley suffered a serious injury near the end of their Premier League clash but ended the week in style with his first goals in the FA Cup.

After several shocks already in the third round, including sixth-tier Macclesfield knocking out holder Crystal Palace, another one looked possible when Colby Bishop raised the roof at Fratton Park by putting Portsmouth ahead after three minutes against Arsenal, firing in a rebound after a save by Kepa Arrizabalaga.

Record 14-time Cup winner Arsenal was only behind for five minutes, though, as Portsmouth was unable to deal with a set-piece delivery and the ball went in off home player Andre Dozzell.

Martinelli glanced in Noni Madueke's corner in the 25th minute to put Arsenal in front and then hit the post soon afterwards from close range.

Madueke put a penalty wide just before halftime to keep Portsmouth in contention, but Arsenal eased away after the break as Martinelli converted from a superb pass by Gabriel Jesus.

He completed his hat-trick with a header as Portsmouth was again unable to defend from an Arsenal set-piece – the 17th goal Arsenal has scored from a corner this season.

"We started the game exactly how we didn't want to, giving them hope and momentum but we managed to turn things around," Arsenal manager Mikel Arteta, who made 10 changes to his starting line-up, said.

"We had to fight back and credit to [Portsmouth] because they make it difficult for us, especially in the early stages."

Arsenal is still challenging for silverware on four fronts and faces Chelsea in a Carabao Cup semi-final first leg on Thursday (AEDT).

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