Borussia Dortmund have sorely missed an “old hand” like this – but there is also a big loser

"I was looking for him," said Niko Kovac, who was about to send Carney Chukwuemeka to find Konstantinos Karetsas. "Then, just like that, he came round the corner," the Borussia Dortmund coach continued on DAZN. Kovac could then bring on the Greek for Serhou Guirassy, who had a thigh injury.

Karetsas had already revealed that he was in the toilet around the time Guirassy went off. The new signing returned in time to come on early in BVB's hugely important 2-1 home win against Real Betis on matchday four of the Champions League.

UEFA awarded him the man-of-the-match trophy after the final whistle. "Fabio Silva deserved it. He scored a goal and provided an assist," said Karetas, whose low shot with his stronger left foot made it 2-1, his first goal for BVB.

That goal was not the only sign of how much Karetsas brought to Borussia's play on Wednesday evening, or how much more he could bring in future. The 18-year-old, whose birthday is in two weeks, plays with creativity and a love of the game. His excellent technique helps him produce moments of surprise.

Konstantinos Karetsas at BVB "like a rabbit"

For his goal, Karetsas received the ball from Silva and immediately cut inside. Then, contrary to expectations, he moved slightly infield before shooting through the opposing defender's legs, hiding the shot from the goalkeeper. That was enough to wrong-foot Alvaro Valles, who had earlier made several strong reflex saves.

"You could see that Kosta is a really good footballer. Not just because he scored the goal, but because he's always making clever little turns. Like a rabbit," said Kovac. "He's difficult to defend against. He has a lot of good stepovers. He brought a lot of impetus. I also thought he and Fabio combined really well up front. I liked that."

Karetsas said he had received no instructions from the Dortmund coach, given the circumstances of his introduction. "I just played my game; they gave me a lot of space," explained the 14-cap international. His start at BVB was hampered by circulatory problems that arose against Villarreal and a lateral ligament injury in the away game against Union Berlin, costing him four matches in total.

Konstantinos Karetsas is the attacking player BVB were missing

Moving from Genk to Dortmund also required an adjustment. "The biggest step from the Belgian league to the Bundesliga is the physical one," he said. "I'm definitely still growing into that and can keep improving. I don't think I needed time to settle in from a footballing point of view."

Karetsas has already shown enough to suggest he will be good for the Westphalian club. They have sorely missed an attacking player with his creativity and carefree approach.

Kovac even gave him something of a free pass, unusual for the coach. With Guirassy likely to miss at least the league match against Elversberg in three days' time, Karetsas looks highly likely to play.

Things could get even harder for Ethan Nwaneri at BVB

"So he'll probably start the next few games while Serhou is out," said Kovac. He then appeared to realise he had revealed something he would usually keep to himself and added: "Probably. I don't know yet. We'll see." Karetsas, for his part, is ready for more: "I feel good and I'm healthy."

For Ethan Nwaneri, Karetsas's return is bad news. Karetsas had already provided the assist for the late equaliser to make it 2-2 as a substitute in Munich last weekend, and he is likely to make it even harder for the Arsenal loanee to get back into the team.

The Englishman started four consecutive league games and also came on early twice during that period, including in the aforementioned Villarreal match, when Karetsas suffered circulatory problems. But the 19-year-old had no end product. He showed promise and had goalscoring opportunities, but also turned in quiet performances.

Ethan Nwaneri has slipped down the pecking order in BVB's attack

Kovac's decision to take him out of the starting line-up was no surprise. Nwaneri has been on the bench for the past five competitive matches and came on only in stoppage time against Betis. The match away to Bayern was even more disappointing for him.

In Munich, Kovac brought on Marcel Sabitzer, Chukwuemeka, Karetsas, Silva and even Samuele Inacio, who had barely featured before then. All are attacking players, like Nwaneri. For the first time in his Dortmund spell, he spent the entire 90 minutes on the bench. Nwaneri has slipped behind Jobe Bellingham, Karetsas, Chukwuemeka and Sabitzer in the pecking order for the positions behind the striker.

Arsenal will surely not welcome that, especially as Nwaneri's previous loan to Olympique Marseille in the second half of last season went badly wrong. The London club are said to have a clause allowing them to recall their player in the winter if they give BVB early notice. That would reportedly save Borussia up to five million euros.

Wednesday evening could be a turning point for both players. Karetsas impressed with his drive and is beginning to emerge as a potential key figure for BVB. Meanwhile, Nwaneri is falling behind in the competition for places, raising questions about his position. For now, he is Borussia's only loser.

BVB fixtures: Borussia Dortmund's next matches