Ex-Arsenal defender Matthew Upson has warned that his former club cannot afford to lose the tenacity of star forward Alexis Sanchez and, if pushed, would opt to keep the Chilean over Mesut Ozil this summer.

Both players are heading towards the final 12 months of their respective contracts and talks over potential extensions have been shelved until the end of the season.

While the influential Sanchez has scored 25 goals in 47 appearances across all competitions so far this term, divisive playmaker Ozil, frequently criticised for failing to exert his influence on games, has received yet more flak over recent weeks for a perceived lack of impact.

Quizzed as to which of their two most expensive signings Arsenal should aim to retain heading into an uncertain transfer window that is likely to be shaped by the future of underfire boss Arsene Wenger, Upson, who appeared 56 times for the Gunners over a six-year spell between 1997-2003, joined Martin Keown in extolling the virtues of Sanchez.

"They are both incredible players so it's a difficult choice and ideally Arsenal would keep both of them," he told bwin.

"If pushed on only keeping one, I'd personally keep Sanchez. I don't think they can afford to lose someone with his energy and determination on the field.

"I'm not saying Ozil isn't committed, but Sanchez displays it on a more regular and intense basis. I think the players look at Sanchez and are inspired to play with him, because he doesn't give up. That's a powerful thing that you can't lose."

Alexis Sanchez and Mesut Ozil
It remains to be seen if Alexis Sanchez and/or Mesut Ozil will remain at Arsenal this summer

Sanchez, who helped keep Arsenal's slim top four hopes alive by sparking a 2-0 victory over Southampton in midweek, and in doing so became just the fifth player in club history to tally 20 Premier League goals in a single season, has attracted attention from top-flight rivals Chelsea and Manchester City as well as Bayern Munich, Paris Saint-Germain, Atletico Madrid and Inter Milan.

Super Lig giants Fenerbahce have been mentioned in connection with a possible swoop for Ozil, who recently reiterated that he feels "comfortable and happy" in London.