Photos: Forgotten defender joins Mesut Ozil, Alexis Sanchez in Arsenal training

Per Mertesacker trains with the Arsenal squad ahead of the visit of Watford...

Per Mertesacker trained with Arsenal stars Mesut Ozil and Alexis Sanchez as Arsene Wenger’s players geared up for the visit of Watford at London Colney on Monday afternoon.

The German defender has been sidelined with a serious knee injury for most of the 2016-17 campaign but the towering centre-half was named on the bench for Arsenal’s 5-0 win against EFL Cup finalists Southampton in the FA Cup fourth round at St Mary’s on Saturday evening.

Arsenal signed Shkodran Mustafi in a £35m deal from La Liga outfit Valencia in the summer transfer window and the defender is currently ahead of Mertesacker and Gabriel Paulista in the pecking order.

German midfielder Ozil joined his compatriots in the training session at London Colney as the Gunners prepare for the challenge of beating Watford on Tuesday night before their short trip to Premier League leaders Chelsea on Saturday.

Here is a round up of the best photos from Arsenal’s training session.

Pierre-Emerick Aubameyang
Thomas Tuchel praises 'fantastic' Arsenal star Pierre-Emerick Aubameyang
Callum Hudson-Odoi
Thomas Tuchel sends message to Chelsea FC star Callum Hudson-Odoi
Gary Lineker
Gary Lineker reacts to Trent Alexander-Arnold's display in Liverpool FC's 4-2 win
Tottenham striker Harry Kane (Photo: Harry Kane / Instagram)
Man United planning 'huge' offer for Tottenham striker Harry Kane - report
Ole Gunnar Solskjaer
Ole Gunnar Solskjaer sends message to Man United about summer signings
Pierre-Emerick Aubameyang
Thomas Tuchel praises 'fantastic' Arsenal star Pierre-Emerick Aubameyang
Callum Hudson-Odoi
Thomas Tuchel sends message to Chelsea FC star Callum Hudson-Odoi
Gary Lineker
Gary Lineker reacts to Trent Alexander-Arnold's display in Liverpool FC's 4-2 win
Tottenham striker Harry Kane (Photo: Harry Kane / Instagram)
Man United planning 'huge' offer for Tottenham striker Harry Kane - report
Ole Gunnar Solskjaer
Ole Gunnar Solskjaer sends message to Man United about summer signings
Top 50 Muslim footballers: Arsenal, Chelsea FC, Liverpool FC and Man United stars feature
Top 50 Muslim footballers: Arsenal, Chelsea FC, Liverpool FC and Man United stars feature