Arsenal head coach Mikel Arteta expects to have to delve into the transfer market with Shkodran Mustafi’s injury worse than originally feared.

The Gunners ended the delayed 2019-20 Premier League season with a 3-2 win over Watford, who were relegated to the Championship, thanks to a first-half brace from captain Pierre Emerick-Aubameyang and Kieran Tierney’s first goal for the north London club.

But having already ruled Mustafi out of next weekend’s FA Cup final meeting with Chelsea, Arteta revealed how he believes the Germany international will miss the September 12 start of the 2020-21 season, joining fellow defenders Calum Chambers and Pablo Mari in the treatment room.

While Arsenal do have William Saliba available for the new campaign after a season on loan at St Etienne, Arteta stressed the need to make sure he has enough cover at the back.

Asked if Mustafi would be out long-term, he replied: “I think so. It looks a really nasty injury again.

“We have lost Calum Chambers the week after I arrived here, we lost Pablo as well for three months.

“Now we’ve lost Musti so at the back we’re really touched and short. Musti has been playing really consistently and at a really good level with me.

“He pulled the tendon off the bone in his hamstring and that’s normally a lot of weeks.

“I already mentioned three central defenders that are not available and we haven’t had them available for a long time during the season. And we will have to address that.”

Arsenal led 3-0 after just 33 minutes at the Emirates Stadium, but Troy Deeney replied from the penalty spot before the break and former Gunners striker Danny Welbeck cut the gap to one midway through the second half.

Watford could not avoid the drop alongside Bournemouth and Norwich, though, and captain Deeney admitted he could have played his last game for the club, after a five-year stay in the top flight.

“I will be having a knee operation next week,” said Deeney.

“Clubs can go in different directions and players can. If that is my last game, I am happy I went out on my shield.

“I am a simple man. Did I go out and do everything I could? Yes. Was it good enough? No.

“It’s heartbreaking for the people who work behind the scenes and we feel sorry for them.

“As a club and as a community we will go again. Ultimately we have not been good enough, there’s no point dancing around it.

“Things happen in football. I have been here 10 years, if it is my time to go, it is my time to go.”