London, Apr 27 (IANS): Down to 10 men and without their coach less than 15 minutes into their Europa League semi-final first leg here against Arsenal, Atletico Madrid came from behind to secure a 1-1 draw and stay alive in the battle to reach the final.

Not even the most optimistic Arsenal supporter in the stands at London's Emirates Stadium could have expected the kind of start the Gunners got during Thursday night's game, reports EFE news agency.

A pair of unnecessary and clumsy challenges by Atleti defender Sime Vrsaljko saw him sent off in the 11th minute and his coach, Diego Simeone, was tossed minutes later for continuing to loudly protest the ejection.

The hosts and their fans, already breathing a sigh of relief over Simeone's decision to not start Diego Costa - a nemesis for Arsenal during his time with Chelsea - seemed to have everything going for them.

Atleti goalkeeper Jan Oblak kept his side in the match, impressing with good stops against Alexander Lacazette and Danny Welbeck.

At the other end, Gunners keeper David Ospina had a quiet first half and was troubled only once, an effort in the 33rd minute by Antoine Griezmann.

The pattern continued after the break, with Atletico bending but not breaking and even getting the occasional chance with deep balls behind the high-pressing Arsenal defenders.

When the hosts finally scored, it was due to a mistake by the Colchoneros, a botched clearance by Griezmann that gave the ball to Arsenal's Jack Wilshere, whose cross led to Lacazette's goal in the 61st minute.

The Gunners got plenty more chances after that, but failed to convert on any of them.

Atletico never lost heart and their discipline and tenacity were rewarded in the 81st minute when Arsenal defender Laurent Koscielny misjudged a long ball from Jose Maria Gimenez. The ball ended up on the foot of Griezmann, who scored with Ospina out of position and Shkodran Mustafi toppling to the ground on the goal-line.

Arsenal's last chance to win, a Lacazette strike from point-blank range, was snuffed out by Oblak, leaving the tie up for grabs as the teams prepare for next week's second leg at the Wanda Metropolitano in Madrid.