Ex-England striker Gary Lineker urges Arsenal to buy a striker this month

Arsenal may find goals hard to come by unless they strengthen. Photo: PA

Gary Lineker believes it is "essential" Arsenal sign a new striker during the transfer window if they want to challenge for major silverware.

Gunners boss Arsene Wenger is refusing to panic buy a replacement for Olivier Giroud, who has been ruled out until the New Year with a broken tibia.

Giroud's injury has limited Wenger's striking options to Alexis Sanchez, who is more effective as a winger, and the inexperienced Yaya Sanogo and Joel Campbell.

Lukas Podolski can play up front but has been linked with a move away from the Emirates Stadium, while another possibility, Theo Walcott, is sidelined with a knee problem.

Former England marksman Lineker believes Wenger must add firepower to his squad before the transfer window closes on Monday.

Sanchez was on target in Arsenal's win over Besiktas. Credit: PA

"Arsenal needed to sign a forward whether Giroud was injured or not," said Lineker, who was speaking as part of Walkers' 'Do Us A Flavour' campaign.

"Now that he's injured it's essential for them really if they're to compete for major titles

"Forward is one position where they needed to strengthen. You could say in midfield too, but particularly up-front.

"If they could add a player who could guarantee 25-goals a season that would be hugely beneficial to them.

"Arsene has showed a lot of faith in Giroud and he's a good player who will score goals, but he's not hugely prolific and lacks a bit of pace to be that."

Sanchez operated as lone striker in Wednesday night's 1-0 victory over Besiktas and rewarded Wenger's faith by opening his Arsenal account with a goal that secured the Gunners' place in the Champions League group stage.

However, Lineker shares a widely-held belief that the £35million signing from Barcelona is better suited to a wider role.

"Striker isn't Sanchez's natural position, he prefers it out wide, certainly on the right-hand side of a three," Lineker said.

"I'm sure he can play striker because he's a terrific player, but I'm not sure it brings out the best in him.

"He's better when he's facing people and going at them, rather than having his back to goal."