Arsene Wenger reckoned that leaving his leading marksman Alexis Sanchez on the substitutes bench had been a "debatable" decision but it was one that appeared to backfire on the Arsenal manager in the 3-1 defeat at Liverpool on Saturday.

There had been plenty of surprise at Anfield when the Arsenal team sheet showed no place in the starting XI for either Sanchez or in-form Theo Walcott in such an important clash in the battle for Champions League places.

Wenger said he felt the more muscular threat offered by Danny Welbeck and Olivier Giroud, who earned the starting spots, would be important as Arsenal would need "to fight in the air as well."

Yet when his side had been outplayed and looked toothless at two goals down after 45 minutes, Wenger evidently had no option but to bring on the livewire Chilean at halftime.

Sure enough, the man who has scored 17 league goals this term did help transform the game, making his first-half absence seem all the more puzzling. It gave the impression of being too little, too late.

Providing Arsenal with an injection of fight and enterprise, Sanchez not only laid on the goal for Welbeck but also helped energise the rather hapless-looking Giroud, who headed against the bar early in the second half.

Asked on BT Sport if he felt the decision not to play Sanchez from the start had backfired on him, Wenger said: "Yes, but I felt as well that the strikers suffered from the fact that we didn't dominate the midfield.

"It's always debatable. In the second-half it was much easier.

"We conceded cheap goals, and you do not expect that in a game like this. We came back in the second half, responded well, but didn't perform at our level in the first half."

The defeat, at the onset of another crucial week for Arsenal with Bayern Munich poised to end their latest Champions League odyssey, is bound only to raise further questions over Wenger's decision-making among his ever-more vociferous band of critics.

Having moved back to fifth place and with Liverpool now having leapfrogged his side, the 67-year-old's hopes of seeing another season of Champions League combat with the Gunners are looking increasingly uncertain.