Ethan Nwaneri wrongly shown red card after just 18 SECONDS as Arsenal loanee endures nightmare afternoon with Borussia Dortmund against Union Berlin

Only 18 seconds into the Bundesliga encounter, the 19-year-old Englishman launched into a high-speed sliding challenge on Union Berlin defender Tom Rothe. Referee Schlager immediately produced a red card, leaving the teenager stunned as he faced an instant dismissal.

However, the official quickly realised he had pulled the wrong card from his pocket. Schlager waved away the red card with his left hand before correctly brandishing a yellow, prompting a wry smile from Dortmund head coach Niko Kovac on the touchline.

Despite the reprieve, the Arsenal loanee endured a frustrating afternoon. Nwaneri failed to influence the game and was substituted shortly after the 60-minute mark, capping off a difficult outing in Germany.

Speaking to Sky after the final whistle, Dortmund goalkeeper Gregor Kobel admitted his initial shock at the referee's blunder. "I thought I was seeing things," the Swiss shot-stopper revealed when asked about the momentary confusion.

Kobel then offered a blunt assessment of his young team-mate's rash tackle. The challenge, which caught Rothe's ankle with an exposed sole, was dangerously close to warranting a legitimate dismissal had the contact been slightly higher.

"The foul was right on the borderline," Kobel added. "I don't know whether you need to go into a challenge like that."

Beyond the early drama, the stalemate highlighted broader issues for Dortmund, who drafted in Nwaneri from Premier League champions Arsenal over the summer after Giannis Konstantelias suffered a cruciate ligament tear on the opening matchday. Despite the reinforcements, sporting director Nils-Ole Book criticised the team's collective lack of bravery against Union.

"We're disappointed. We wanted to do a lot more," Book stated. "To get in behind, you need to play with more courage all over the field. We started doing that far too late."

The Dortmund chief emphasised that tactical improvements are urgently required for the squad to reach their potential. "When we're bolder, we play really good football and are able to put pressure on our opponents," Book concluded.

Following a narrow 1-0 defeat to Bodo/Glimt earlier in the week and this domestic stalemate, Dortmund are desperate to regain their momentum. They turn their attention back to Champions League action on Tuesday when they face Azerbaijani outfit Sabah.

Nwaneri, who has made seven appearances so far this season, will be hoping to secure his first starting berth in continental competition. A commanding victory is vital for Kovac’s side as they aim to claim their second win of the tournament and ease the mounting pressure on the squad.