Leksand started with both the big star Max Véronneau and the team captain Patrik Zachrisson injured.
Dalalaget got a dream start after Calle Själin knocked in 1-0 from distance with a shot.
The reply, however, came quickly when Oskarshamn's Kom Rosdahl equalized, the assist came from Fredrik Olofsson.
The first period seemed to end goalless, but former Leksand player Philip Samuelsson put 2-1 to Oskarshamn with less than a minute left.
Linus Andersson equalized at the beginning of the interim period for Leksand, minutes later Oskarshamn's Fredrik Olofsson put 3-2 to the guests.
"We have nothing to be ashamed of"
Directly in the third period, Jonas Engström made 4-2 for Leksand and the situation was dark for Leksand.
With 3.23 left of the third period, Leksand's coach Björn Hellkvist timed out and then picked out the goalkeeper.
- We have nothing to be ashamed of at all today, seen over the whole season it was not really approved, we wanted to the quarterfinals.
- They are very effective and we are not, we do not put the pucks, says Björn Hellkvist, says Leksand's coach Björn Hellkvist in C more.
Historic for Oskarshamn
Leksand fought feverishly, in vain.
The match ended 4-2 and Oskarshamn bounced back after the defeat yesterday.
Now the Smålanders are ready for the quarterfinals for the first time in the club's history.
- It's cool, it's hard to take in here and now, says Oskarshamn's faithful servant Jonas Engström in C more.
- These matches mean a lot to me even after all the years you have been in the club, he says.
Now Oskarshamn meets Rögle in the quarterfinals.