France striker Randal Kolo Muani warned he was "getting better" after scoring two and assisting another in Eintracht Frankfurt's 4-2 derby defeat of visiting Darmstadt in the German Cup on Tuesday.

The five-time Cup winners needed to come from behind for the victory and once again it was in-form Kolo Muani who proved crucial for the home side in the last 16.

"We played well and we fortunately equalised quickly, then we were able to put a lid on it," he told Sky.

"I'm getting better at playing to my qualities."

Despite Darmstadt sitting a division below Frankfurt, the visitors sit atop the Bundesliga 2 table and have lost only one game in all competitions this season.

Frankfurt, who have only lost once since mid-October, hit the lead after just six minutes through Kolo Muani, whose perfectly weighted header evaded the outstretched fingertips of Darmstadt keeper Marcel Schuhen.

The home side almost doubled their lead 15 minutes later through midfielder Mario Goetze, but the 2014 World Cup winner's shot was well blocked by Schuhen at point blank range.

Darmstadt then turned the game on its head, scoring twice in two minutes through Mathias Honsak to take the lead.

The first came when Darmstadt's pressing forced Frankfurt captain Sebastian Rode into an error, while the second was a length of the field effort kick-started by a long pass from Schuhen and finished by cool shot from Honsak.

With one minute before the break, Goetze found forward Rafael Borre in the box and the Columbian hammered home an equaliser.

Kolo Muani helped the home side reclaim the lead after 62 minutes, heading a cross into the path of Japan's Daichi Kamada who hammered home.

Kolo Muani added another in the last minute of regular time, Goetze catching Darmstadt on the break to find the France striker in space, who side-footed home.

Earlier, Austrian defender Philipp Lienhart scored an 87th-minute header to help Freiburg earn a 2-0 win at Sandhausen on Tuesday to book a place in the German Cup quarter-finals.

Last season's losing finalists Freiburg, currently sixth in the Bundesliga, outplayed their second-division opponents but the game looked set to go into extra time before Lienhart glanced the ball into the net from a Vincenzo Grifo corner.

Striker Nils Petersen, brought off the bench with less than 10 minutes to play, added a second in the fifth minute of injury time to put the game beyond doubt.

After the match, an exhausted Lienhart credited his side for "rewarding ourselves" after "a hard bit of work".

Sandhausen have now lost four of their past five games and currently sit in 15th in the second division, one point off last spot.

They sat deep and looked content to push the match into extra time, having defeated neighbouring Karlsruhe 8-7 on penalties in the previous round.

On Wednesday, Nuremberg host Fortuna Duesseldorf in an all second division clash, while 2020-21 winners Borussia Dortmund travel to Bochum.