Gabriel Martinelli hit the headlines for the right reasons by scoring a hat-trick as Arsenal overcame an early scare to thrash Championship strugglers Portsmouth 4-1 in the FA Cup third round.

Mikel Arteta’s Premier League leaders fell behind less than three minutes into a rain-soaked contest at Fratton Park when Pompey captain Colby Bishop finished from close range.

Andre Dozzell’s own goal quickly levelled the tie before Brazil forward Martinelli struck either side of Noni Madueke’s penalty miss to put the Gunners in control.

Martinelli, who was widely criticised for attempting to push the injured Conor Bradley off the pitch during Thursday evening’s goalless draw with Liverpool, completed his treble in the 72nd minute.

The Brazil forward also missed an open goal at 2-1 as 14-time cup winners Arsenal began four successive away games in four different competitions by reaching round four for the first time in three seasons.

Manager Arteta made 10 changes for the visit to Hampshire, while injury-hit Portsmouth made four to the team thrashed 5-0 at Bristol City on New Year’s Day.

Fired-up home fans created a raucous atmosphere from the first whistle and were rewarded with a shock early opener.

Following good work from Harvey Blair down the left, Conor Chaplin’s initial effort was only parried by Gunners goalkeeper Kepa Arrizabalaga, leaving Pompey striker Bishop to slam home on the rebound and claim his first goal since August.

Portsmouth – a point above the Championship relegation zone – had not beaten Arsenal in the previous 22 meetings between the clubs, dating back to 1958, and were pegged back in scrappy fashion five minutes later.

Eberechi Eze’s corner from the left caused confusion in the hosts’ box and Dozzell – the son of former Tottenham midfielder Jason – diverted the ball into his own net under pressure from Christian Norgaard.

Forward Blair threatened as Portsmouth continued to make life uncomfortable for their opponents.

But Arsenal again showed their potency from set-pieces in the 25th minute when Martinelli rose to head in Madueke’s corner from the right, albeit replays suggested a goal kick should have been awarded.

Martinelli curled narrowly wide after a superb through-ball from Mikel Merino before somehow scuffing against the left post with the goal gaping following Ben White’s low cross from the right.

Arsenal’s profligacy persisted. After going down under a challenge from former Gunners youth player Zak Swanson, Madueke fired wide from the penalty spot in the 43rd minute at the end of a stuttering run-up.

Two-time FA Cup winners Portsmouth returned for the second half with plenty of optimism following the series of let-offs.

Chaplin had a close-range effort blocked following a corner before Martinelli doubled his tally in the 51st minute by sliding in at the back post to turn home Gabriel Jesus’ low cross from the right in front of the 3,000 away supporters.

Injury-plagued Gunners forward Kai Havertz came on for the final 21 minutes to make his first appearance since the opening weekend.

And Portsmouth’s resistance was dealt a fatal blow three minutes later.

Arsenal again capitalised on a corner, with Martinelli claiming the match ball by heading through the hands of Pompey keeper Josef Bursik and into the roof of the net from another Madueke delivery.