Belgian boss Wouter Vrancken was without 10 players through various ailments and the Scottish outfit were dealt another blow in the 22nd minute when defender Jamie McCart put through his own goal in calamitous fashion.

Thun doubled their lead in the 33rd minute through striker Brighton Labeau after more poor defending, this time from skipper Stephen Kingsley – who went off later with an injury – and then Furkan Dursun grabbed a third in the 56th minute before Jambos defender Stuart Findlay reduced the deficit in the 82nd minute with a header.

Hearts were left with one Conference League point out of nine following a 1-1 home draw against Nordsjaelland and a 2-0 defeat away to Trabzonspor.

Thick smoke from a pyro halted the game soon after kick-off but when play resumed after a lengthy delay – there were nine minutes added on at the end of the first half – Hearts winger Josh McPake drew a save from Niklas Steffen with an angled drive that lacked real power.

In the 20th minute McPake’s effort from 25 yards after he had drifted in from the left had the power but was beaten away by the Thun keeper.

There appeared to be nothing untoward on the horizon but then came a Hearts horror show.

There was no real pressure on the Jambos goal when a long ball came into the box but with Lucien Dahler at his shoulder, a simple pass back from McCart somehow evaded Hearts keeper Beau Reus and slipped into the corner of the net.

Thun’s second goal was also gift-wrapped.

The home side broke clear and with pace following a Heart set-piece and when Nils Reichmuth crossed into the box from the right, Kingsley stuck out a leg to clear but the ball went straight to Labeau who swept it into the net from 10 yards out.

Dursun was shown a yellow card for a forearm challenge into the face of Findlay, and it perhaps deserved more punishment.

The interval gave the Tynecastle side time to reset but three minutes after the break, Reus made a diving save from Dursun and an even better one from Reichmuth moments later.

However, the keeper was beaten once again when Dursun got his toe to a Reichmuth cross.

On the hour mark, Nico Maier raced clear of the Hearts defence but although his chip beat Reus, it sped wide of the target.

The night got worse for the rattled visitors as injured Kingsley was replaced by 19-year-old Matthew Gillies, called back from a loan spell at Stenhousemuir.

Hearts were sporadic in their threat.

Malachi Fagan-Walcott’s header from a Jordi Altena free-kick was brilliantly saved by Steffen.

In the 78th minute Jan Bamert had the ball in the net after Steffen tipped a free-kick from substitute Nassim Zoukit on to the bar but was ruled offside, before Findlay headed in a consolation from another Altena free-kick.