Rögle, who by SVT Sports expert Jonas Andersson has been tipped to win the Swedish Championship gold, got hot in the first quarter against Oskarshamn.
After a goalless first period, more began to happen in the middle of the night.
Oskarshamn got the chance in powerplay several times and in the end Rögle was forced to give way.
Hynek Zohorna put 1-0 to Oskarshamn with five minutes left of the second period, in games five against four.
Rögle's equalizer also came in powerplay.
When Oskarshamn's Brian Cooper was sent off for tripping, Dennis Everberg set the equalizer.
"We have nothing to lose"
Two minutes later, Oskarshamn shocked Rögle again and took the lead with 2-1 through Robin Norell, who also became the winner.
The match ended 2-1 to Oskarshamn as the rattlesnake won the first quarter-final meeting.
- We follow our game plan and do what we are supposed to, says Norell in C more.
- We really have nothing to lose, he says.