Schlager's deflected effort drew Salzburg level on aggregate
Having lost 2-0 to Marseille in the first leg of their Europea League semi-final, the Austrian side needed to win by the same margin on home truf to force extra time, something that most onlookers saw as unlikely.
However, Amadou Haidara got the comeback off to the perfect start after 53 minutes of the game with a fine individual effort, which began a huge push from the hosts as they grew in confidence.
That push was rewarded just 12 minutes later as the Austrians found their second.
Despite two Salzburg players being in an offside position as Haidara crossed, play was waved on and when Marseille failed to clear, Schlager controlled the loose ball and fired at goal, with his effort deflecting in off the hapless Bouna Sarr.
That goal levelled the tie on aggregate, leaving extra time and penalties a distinct possibility.