Identifying Stumbling Blocks for Borussia Dortmund's Europa League Campaign

Borussia Dortmund's march on the UEFA Europa League title seems almost inevitable at this point.

That comes with the territory when a team dismantles an experienced side like Porto in the round of 32 and brushes off Tottenham Hotspur with an aggregate score of 5-1 in the last 16.

"Borussia Dortmund are far too good for the Europa League and two-goal striker Pierre-Emerick Aubameyang belongs on a bigger stage" wrote John Cross for the Mirror after Thursday's 2-1 win over Spurs.

It indeed looks like the Black and Yellows are on a different level compared to the rest of the teams still in contention for Europe's lesser competition. 

The round-of-16 tie with Spurs was supposed to be a match on eye-level between two sides many tipped to play the final in Basel on May 18. As the expected-goals graphic from Michael Caley points out, it became a demonstration of how much better the second-placed team of the Bundesliga are than their counterparts from the Premier League at this juncture:

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Two-legged xG map for BVB-Tottenham. This tie showed Spurs how far they still have to go to reach Europe's elite. pic.twitter.com/hkJJp0Q8Ae

— Michael Caley (@MC_of_A) March 17, 2016"

Of course, Spurs didn't play a first-choice team in either of the two matches against Dortmund, but the Black and Yellows were so superior that it's difficult to envision a scenario in which even Mauricio Pochettino's best XI would've mounted a challenge for them.

In a poignant sign of how differently the two sides value the Europa League, Spurs striker Harry Kane played a grand total of 14 minutes over the two games, whereas Dortmund's central forward Pierre-Emerick Aubameyang scored three of his side's five goals and played all but eight minutes of the tie.

His sensational strike in the 24th minute at White Hart Lane was the final nail in Spurs' coffin:

Now Dortmund await their draw for the quarter-finals. Whomever former BVB hero Alexander Frei picks out on Friday will have a mountain to climb if they want to get past the Black and Yellows.

That being said, there are a few areas the Ruhr side need to be wary of on their quest for Europa League glory. Here are a few of those potential stumbling blocks.

Individual Mistakes

Yes, we start with a fairly obvious one.

Neven Subotic gifted Heung-Min Son Spurs' only goal of the tie in the 74th minute on Thursday when he horribly misjudged a pass back to goalkeeper Roman Weidenfeller. 

That was only the fourth goal Dortmund conceded in the 14 games of 2016, and it came out of nowhere, seeing as the Serbian defender had played very well to that point, but it was a reminder of how quickly things can go wrong.

It was also reminiscent of the first half of the season, when the Black and Yellows regularly made individual mistakes, as WhoScored.com pointed out on Twitter earlier this year:

Goalkeeper Conundrum

Roman Weidenfeller has done nothing wrong in his appearances this season, all but one of which came in Europe, but it still feels like a gamble from head coach Thomas Tuchel. Roman Burki is the No. 1 in the Bundesliga, and it's difficult to understand why that shouldn't be the case in Europe.

Tom Dulat/Getty Images

Thirty-five-year-old veteran Weidenfeller gets these games out of gratitude for good sportsmanship towards his newly acquired competitor in goal early in the season, but as the games get more and more important, Tuchel should make the switch to Burki.

The Switzerland international showed he's more than ready against Porto—as Weidenfeller missed both matches—and, most notably, with an incredible shot-stopping performance against Bayern Munich.

Squad Depth in Attack

Dortmund's team looks strong enough to beat out the seven other remaining teams in the competition. As Cross alluded to, they are a UEFA Champions League side playing in the Europa League for one campaign. 

BEN STANSALL/Getty Images

Still, though, the Black and Yellows rely heavily on the health of their attacking players, as there are no viable back-up solutions for Aubameyang, Marco Reus or Henrikh Mkhitaryan.

The Gabonese "shines through with his confidence," as Tuchel put it after the game, per the club's official website. "If he continues to work hard and stays level headed, then anything is possible."

One injury to their star striker would put a massive stoke in Dortmund's wheel.

Of course, we could say much of the same things about all the other sides that made it to the quarter-finals, and that's why Dortmund are still heavily favoured (per Oddschecker.com) to hoist the trophy in St. Jakob-Park in May.

Just don't expect it to be as smooth a ride as the first two knockout stages were.

Lars Pollmann is a Featured Columnist writing on Borussia Dortmund. He also writes for YellowWallPod.com. You can follow him on Twitter.