Mertesacker, 30, has been a regular in the heart of the Gunners defence since his £8 million move from Leverkusen in August 2011, making 157 total appearances over the past four seasons, while adding seven goals.
The German World Cup-winner has captained the club for long periods since last season due to injuries to the now-departed Thomas Vermaelen and Mikel Arteta, but his performances this term have come in for considerable criticism.
A dreadful outing in last night’s 3-1 Champions League last-16 defeat to Monaco lead fans to call for manager Arsene Wenger to drop him for new signing Gabriel Paulista, who arrived from Villarreal last month with a reputation as one of Europe’s top emerging centre-backs.
Keown doesn’t believe Wenger will make the switch at this point but, with both the £11 million Brazilian and versatile Calum Chambers snapping at his heels, can see the towering defender being made expendable down the road much like Vermaelen was in the summer.
“I think he’s under pressure. Gabriel is there, ready to play, and it looks as if Calum Chambers will become a centre half, rather than a right back,” he wrote in his ‘Tackle Keown’ column.
“If things don’t go well, it looks like Wenger has the necessary players to replace him, unlike in the past. You only get so long under Wenger to stake a claim. He always invests time on each player, but he may want to invest time in someone else now.
“Look what happened with Thomas Vermaelen – it’s debatable whether Mertesacker is better.
“I think Wenger still believes in him, he feels he gives organisation to the defence. But it’s a balancing act with his lack of mobility.”