The Serbia international departed Frankfurt after a hugely productive 2018-19 season, during which he scored 27 times in all competitions.
Madrid paid €60million to sign him, though the move has failed to work out as hoped. During his 18 months in the Spanish capital, Jovic managed just two goals in 32 appearances, albeit he started on just 11 occasions.
However, a return to familiar territory has helped the 23-year-old - who will spend the rest of the season on loan in Germany - quickly rediscover his form.
He scored twice in his first game back, a 3-1 triumph over Schalke, and while unable to find the net as a substitute against Freiburg, he was on the scoresheet once more on Saturday.
On as a second-half substitute once again, Jovic rounded out the scoring for Adi Hutter's in-form side as they thrashed Arminia Bielefeld 5-1 on the road.
It means the former Benfica player has now managed three goals from four attempts in just 76 minutes of action for Eintracht - and he is also having a big impact on one of his team-mates.
Filip Kostic provided two assists against Bielefeld and, according to Hutter, has been rejuvenated by the arrival of his countryman.
"I do think that his improvement has a lot to do with the return of Luka, because they got along really well and are friends off the pitch, as well as in the Serbia national team," Hutter told the media.
"So, I think that played a part in it, too. But I felt that when Luka came, Filip's confidence went up a lot."
Andre Silva was the beneficiary of Kostic's work, the Portuguese forward grabbing a first-half brace to take his tally to 14 in 18 league games, equalling a club record previously set by Theofanis Gekas.
"We worked hard for this win and we deserved it," Silva said. "I was in the right place with the first goal, and with the second I hit the ball really well.
"Luka is a great player. We can get even better together and help the team even more."