A late strike from forward Kevin Behrens sent Union Berlin through to the quarter finals of the German Cup, with a 2-1 win at home over Wolfsburg on Tuesday.
"It is a deserved victory," Behrens told German TV.
"We have a great bunch. We're having fun."
In lashing rain and hail, the visitors started stronger, taking the lead after four minutes.
Wolfsburg midfielder Yannick Gerhardt chopped a corner to forward Luca Waldschmidt, who sneaked in behind Union's defense line to tap the ball in and put the 2015 Cup winners in front.
Union responded, scoring just seven minutes later through defender Robin Knoche, who latched onto a curling delivery from Croatian defender Josip Juranovic.
Juranovic, who played every minute in Croatia's run to the World Cup semi-finals before sitting out the third-place game, has two assists in two games since joining from Celtic in mid-January.
Union continued to press after halftime, pinning the visitors back into their penalty box as they pushed for a winner.
With ten minutes remaining, Dutch striker Sheraldo Becker headed a low cross from Rani Khedira goalwards, finding Behrens, who whacked the ball into the net from two metres.
Union lost Niko Giesselmann with three minutes remaining, the defender picking up a second yellow for diving in the box.
The home side held on in the nervy closing stages under attack from Wolfsburg to win 2-1.
Goalscorer Behrens, who now has two goals in three games, said coming off the bench to score in front of Union's home fans was "an outstanding feeling - it's just like how you'd imagine it".
Union manager Urs Fischer said he was "incredibly proud of the squad" for the comeback victory.
"It was enormously important that we scored the equaliser. We played a great second half and stayed calm, then we hit (them with) a lucky punch."
Wolfsburg's manager credited his side's effort in the "intense game", but lamented losing focus in key moments.
"We didn't pay proper attention on two occasions, which led to our defeat."
- Stuttgart strike late -
Earlier on Tuesday, Stuttgart scored two late goals to run out 2-1 winners at Paderborn in the opening Round of 16 clash.
Second-tier Paderborn hit the lead early through an own goal.
Former Arsenal defender Konstantinos Mavropanos tried to pass to goalkeeper Florian Mueller, but hit the ball too sharply, sliding it into his own net.
Paderborn, who have been promoted to the Bundesliga twice in the past 10 years before being immediately relegated one season later, held Stuttgart out and looked to be heading for a victory over their first-division opponents.
With just four minutes remaining, the visitors equalised through Portuguese midfielder Gil Dias, with Mavropanos playing a key role in the lead-up.
A last-gasp header from Stuttgart's Guinean striker Serhou Guirassy gave his side the winner in the fifth minute of injury time.
The goal was the Guinean international's fifth in his last seven games.