By London correspondent Tony Hughes

Arsenal forward Joel Campbell is undergoing a medical with Sporting Lisbon, according to a report.

The Sun claim the Costa Rica international is close to sealing a season-long loan switch to the Portuguese side after a deal was clinched with the Gunners.

Campbell, 24, was not included in the Arsenal squad for their 4-3 defeat by Liverpool last weekend.

It appears that he is now set for his fifth loan move away from the Gunners since joining Arsene Wenger’s side in 2011.

Campbell has had previous spells at Lorient, Real Betis, Olympiakos and Villarreal during what has been a nomadic career.

The right-sided forward had appeared to have established himself as a squad regular last season when he made 30 appearances in all competitions, scoring four goals and supplying six assists.

But Wenger appears to have given Campbell the green light to depart even though Arsenal have not signed a new striker this summer and the manager has suggested that he will continue to play winger Alexis Sanchez through the middle instead.

Sanchez led the line in their 4-3 Premier League defeat to Liverpool last Sunday, with main striker Olivier Giroud still working his way to full fitness after a delayed pre-season.

The France international was given an extended summer break after helping his country reach the final of Euro 2016, where they lost to Portugal.

Arsenal have been linked with a whole host of strikers this summer, and thought they had persuaded Jamie Vardy to sign before he decided to continue his career at Leicester.

The Daily Star claimed last week that they were set to make a £30million bid for Man City striker Wilfried Bony.

Bony only joined City for £28million from Swansea in January 2015 but has notched just six Premier League goals in that time and found it difficult to make the starting line-up, where his path has been blocked by Sergio Aguero.

Another major pursuit has been for Lyon striker Alexandre Lacazette but they had a bid of £29.5million rejected by the Ligue 1 giants for him, while they also missed out on the signing of Gonzalo Higuaín.

In other Arsenal transfer news, a manager says his experienced international defender could move to the Gunners if they find a replacement.