Schalke produced a sensational second-half fightback to draw 2-2 at Borussia Monchengladbach and earn a place in the Europa League quarter-finals via the away goals rule.

After the first leg had finished 1-1 under the closed roof at the Veltins-Arena a week ago, Gladbach seized control of the return fixture by moving 2-0 in front by half-time at Borussia-Park.

Andreas Christensen put Dieter Hecking's side ahead before Mahmoud Dahoud thumped in a second from distance to put daylight between the domestic rivals.

However, Schalke - who are two places and as many points below Gladbach in the Bundesliga - were back in the game and the tie when Leon Goretzka struck with a fortuitous effort in the 54th minute.

And Gladbach were left reeling when Dahoud was penalised for handball in the area, allowing Nabil Bentaleb to convert the resulting penalty that sent Markus Weinzierl's men into the draw for the last eight.

Guido Burgstaller - scorer of Schalke's equaliser in the first leg - steered an early header just wide of the target before Gladbach lost Fabian Johnson through injury.

The home side should have taken the lead in the 18th minute when Raffael's run and cross down the left found Josip Drmic unmarked eight yards out but, in attempting to put the ball out of goalkeeper Ralf Fahrmann's reach, the Swiss forward directed his header the wrong side of the post.

Drmic made amends for that poor miss with a cushioned nod-down from a free-kick that teed up Christensen's opener.

The on-loan Chelsea defender had enough time to take a touch inside the area before aiming a shot at goal, albeit his attempt needed a deflection off Benedikt Howedes to find the net.

In contrast, Dahoud did not need any assistance to get Gladbach's second on the stroke of half-time.

With Schalke backing off, the midfielder let fly with a right-footed rocket that flashed beyond the rooted Fahrmann.

In a deep hole heading into the second half, Schalke's recovery mission was kick-started by Goretzka's fortunate goal in the 54th minute.

A poor clearance from Jannik Vestergaard allowed the midfielder to take aim with his left foot, although his low drive needed a horrible bobble to get beyond goalkeeper Yann Sommer's dive.

Dahoud presented the visitors the chance to draw level when he needlessly thrust an arm out inside his area, giving referee Mark Clattenburg little option but to award a penalty.

Bentaleb converted from the spot - just as he had done in his side's 4-2 Bundesliga loss at the same venue on March 4 - to suddenly put Schalke in the driving seat.

And Schalke stood firm under a late onslaught to progress, leaving Weinzierl's squad as the last German team left standing in the competition