Borussia Dortmund booked their place in the last-16 of the Europa League after overcoming Atalanta in a highly entertaining contest.Leading 3-2 from the first leg, Dortmund were heading out of the competition when they trailed 1-0 with 10 minutes remaining.But Marcel Schmelzer’s equaliser in the 83rd minute was enough to ensure Dortmund’s passage to the next round, with manager Peter Stoger admitting that his side was “lucky” to progress.“Well, effectively, we were a bit lucky,” he conceded, per Goal. “It was only to be expected that it would be difficult, but we certainly made it easier for them in the first half."We were not aggressive or physical enough, and we did not apply what we had spoken about doing beforehand.“That was not the kind of professional game that you have to play on such occasions.”Dortmund, who are among the favourites to win the Europa League, will find out their last-16 opponents today.

Mats Hummels tweeted after Schmelzer scored

One man who thoroughly enjoyed watching Schmelzer send Dortmund to the next round was Bayern Munich defender Mats Hummels.

Hummels spent eight-and-a-half seasons at Dortmund before returning to Bayern in 2016 and he tweeted his former teammate’s name when he levelled the match.

Football fans were confused by Hummels' tweet

The 29-year-old was surprised when his Twitter mentions was suddenly filled with messages from Bayern and Dortmund fans who were confused by Hummels' celebrating Bayern's success.

Check out some of the tweets Hummels received last night.

Pretty crazy, right?

Hummels then responded

Hummels sent another tweet, ridiculing those who questioned his tweet.

“Gotta love the Internet where people try to tell you that you are not allowed to celebrate (with) someone you played for so many years 😂 good night 😁,” he wrote.

While Hummels is on his way to the quarter-final of the Champions League, with Bayern boasting a 5-0 advantage in their round-of-16 matches against Besiktas at the halfway point, Stoger is fully aware that his players need to up their game if they are to win the Europa League.

"We have the right attitude, and the boys have demonstrated that a number of times,” he added.

“Of course, I'm pleased that we are through to the next round, but we have also got a lot to talk about after this match."