The Icelandic international calmly slotted home from close range after Jay Rodriguez had neatly played him in just before the break.

Goalkeeper Diego Penny had a quiet night on his debut, with the Peru international barely troubled.

And after a testing opening spell for the Clarets, with Christian Kalvenes in particular being given a torrid time by a pacy Thistle trialist, Burnley bossed proceedings.

The Clarets had the first real sight of goal on 18 minutes when Kalvenes' centre was flicked on at the near post by trialist Gatis Kalnins, and Gudjonsson, breaking into the middle at pace, headed straight at keeper Craig Hinchcliffe.

And Alex MacDonald's eyes lit up moments later when Steve Jones' low ball found it's way to the back post, only for Marc Twaddle's superb block to deny the youngster a clear strike at goal.

Jones then went close with a fierce daisy cutter that flew just wide of the far post.

Kalnins' deft touch sent Jay Rodriguez away down the inside left channel, but rather than try to curl the ball inside the far post, he opted to look for MacDonald, but as the ball ran across his body, he
sliced his effort wide.

But Burnley went ahead in the final minute of the first half when Rodriguez showed superb control to chest down a raking pass from Graham Alexander, and a perfectly-weighted touch for Gudjonsson to break into
the box and calmly side-foot inside the post.

At the start of the second half, Martin Paterson, Wade Elliott, Kevin McDonald, Chris McCann and Ade Akinbiyi came on for Rodriguez, Jones, Gudjonsson, Alan Mahon and Kalnins.

Two of the substitutes combined on 53 minutes when Elliott's corner was headed back by Michael Duff, and McCann swivelled and shot, but got under the ball and fired over.

McDonald forced a save with a stinging drive as Burnley continued to dominate, but Penny made his first save of note, plunging to his left to turn former Celtic and Sheffield Wednesday midfielder Simon
Donnelly's free kick round the post.

Robbie Blake replaced MacDonald midway through the second half, and with 15 minutes remaining, Clarke Carlisle came on for Kalvenes, but that didn't disrupt the flow of play towards Partick's goal, and Akinbiyi forced a double save from the keeper from a delightful
reverse ball from Elliott.

Penny made a fine stop to hold a deflected effort from the Jags' trialist to maintain the lead, as Gudjonsson's goal proved enough.

Burnley: Penny; Alexander, Duff, Jordan, Kalvenes; MacDonald, Gudjonsson, Mahon, Jones; Kalnins, Rodriguez.
Subs: Kiraly, Elliott, Carlisle, Blake, McCann, Paterson, Akinbiyi, McDonald, Berisha, Kay.

Attendance: 1,162