Substitute Michal Duris scored in injury time to help Plzen draw with AC Milan 2-2 in their final group stage game in the Champions League on Tuesday.
Milan had already qualified for the knockout stage from Group H with Barcelona.
Brazilian forwards Pato and Robinho struck within a minute early in the second half for AC Milan to jump to 2-0.
Pato, regaining his form following a leg muscle injury, scored two minutes after the break after Robinho chested the ball for him to round goalkeeper Marek Cech and score into the empty net.
A minute later, it was Pato who fed his Brazilian teammate to net from 10 meters.
Marek Bakos crossed for David Bystron to pull one back a minute from time and a desperate Plzen was rewarded when Duris tied the score in injury time from close range.
''We took a 2-0 lead but our players were not focused enough toward the end, which opened the way for Plzen to come back,'' Milan coach Massimiliano Allegri said. ''That made me really angry.''
Plzen finished third in the group and earned a spot in the Europa League.
''We had to take a risk,'' Plzen coach Pavel Vrba said on his 48th birthday. ''And the risk paid off.
''I was absolutely delighted with the performance of our players. The draw was a great reward for us.''
Defending European champion Barcelona comfortably won the group with 16 points after a 4-0 victory over Belarus' BATE Borisov. Milan was second on nine and Plzen third on five. BATE won just a point.
With two European superpowers in the same group, Plzen could have hardly hoped for more in its debut Champions League season.
Still, it was by far the best result at an international level for the Czech provincial team.
''A year ago, nobody would even have dreamt about it,'' Vrba said
Milan played without striker Zlatan Ibrahimovic and with Pato and Robinho up front, but the Brazilians failed to impress in the first half.
In a rare chance, Pato didn't capitalize on a defensive blunder by Bystron nine minutes into the match when his angled shot missed.
It was surprisingly Plzen which looked more dangerous than the seven-time European champion.
Czech international midfielder Vaclav Pilar wasted the two biggest first-half chances for the home team: First, his fierce volley from inside the area off a Pavel Horvath corner kick skimmed over the crossbar, and then a smart pass from Horvath he into the side of the net.
Defender Marian Cisovsky headed just wide four minutes before the break.
Plzen lost its key midfielder Petr Jiracek, who was carried off on a stretcher with what seemed to be an ankle injury after a clash with Daniele Bonera in the 27th.
Pato hit the post in the 56th and Cech denied him eight minutes before the final whistle in a one-on-one.
At the other end, midfielder Milan Petrzela and Duris also hit the post in the second half for the Czech champion.
