Olivier Giroud suggests Marc-Andre ter Stegen's second-half save denied Arsenal a certain goal at the Emirates Stadium on Tuesday night.

The Barcelona keeper came up with a smart stop to deny Giroud's header midway through the second term of the Champions League Round of 16 first leg before the visitors opened the scoring through Lionel Messi in the 71st minute.

Giroud felt that the intervention from the German gloveman provided a major turnaround in the complexion of the match which Barca ended up winning 2-0 following a late penalty from Messi.

"It's possibly the turning point," the French striker told Arsenal Player.

"I had a duel with the defender and I think that I headed the ball well but the keeper did very well."

However, Giroud admitted that the Gunners were inefficient in front of goal which ultimately contributed to their downfall.

"We were not cautious enough of their counter-attack [afterwards], which is a model counter-attack, and then they finished it well," he added.

"We couldn't score in the first half after we played well on the counter-attack and were dangerous."

Arsenal head to Camp Nou for the return leg on March 16.