MacIntyre made only one birdie during the third round but he matched that tally at the opening hole when he dialled in his approach to six feet to nudge ahead on his own at ten under.

The Scot parred the next four but was desperately unlucky not to birdie each hole – including a shoehorn at the fifth – however, it was Ritthammer who joined him at the top with a gain from six feet at the fifth.

Casey produced a fine tee shot at the second to card his first birdie of the round and when he rolled in an eight-foot putt at the sixth following a great approach, he made it a three-way tie at the top.

The Englishman then took solo lead after another arrow from the eighth tee to record his third birdie, but he was alone for just a matter of minutes as MacIntyre dialled in to six feet at the seventh to move to 11 under.

Casey made a fine par save at the ninth after sending his tee shot in the sand but there were no such trouble for the final pair.

Despite finding the rough with his first, Ritthammer landed his third shot to two feet for a tap in birdie to join Casey at 11 under, but MacIntyre rolled in his third gain to take the outright lead heading down the back nine.

However, ahead of them, Bernd Wiesberger was motoring up the leaderboard courtesy of a birdie frenzy around the turn.

After a bogey at the second, the Austrian picked up the shot at the fourth before he carded four in a row from the eighth to move in contention at eight under.

The birdie trail continued with a hat-trick from the 13th – where he just missed his eagle putt at the 15th – as he improved his score to 11 under.

It looked as though Wiesberger would join MacIntyre and Casey at the top of the leaderboard after the Scot and Ritthammer took penalty drops after wild tee shots at the 11th.

But MacIntyre salvaged a superb par with a monster putt to maintain his slim lead but his hard work was undone with his first bogey at the next, with Casey taking full advantage.

The 42-year-old fired in yet another iron to close range at the 13th and when he holed out from six feet, he was the leader at 12 under.

Ritthammer bogeyed the 11th but regained the shot at the 13th to move alongside playing partner MacIntyre and Wiesberger, however, the pair soon left the German at 11 under alongside Frenchman Romain Wattel, who eagled the last for a terrific 64.

Wiesberger recorded his sixth birdie of the back nine at the last to set the clubhouse target of 12 under following his superb 64, and moments later MacIntyre joined the Austrian and Casey at that mark with a calm gain at the 14th.

Casey shoehorned a birdie putt at the 15th which would have put him alone at the top, but Ritthammer increased the party at 12 under to four with a gain on the same hole.

But the World Number 17 nudged ahead once again with an arcing right-hander from 35 feet to reach 13 under par with two holes left.

Ritthammer hit back with a gain at the 16th to move to 13 under but he remained one shot behind Casey after a fine tee shot at the penultimate hole led to back to back birdies for the European Ryder Cup star.

Austrian Matthias Schwab made his move to 11 under with five birdies and bogey and jumped up to join Ritthammer thanks to a superb eagle at the last.

Casey could only par the last to give MacIntyre and Ritthammer hope of a potential play-off, but the Scott’s eagle putt slid by the hole before the home favourite’s birdie attempt pulled up just short as the final pair finished at 13 under par.

Wiesberger finished in solo fifth at 12 under, while playing partner Wattel was one shot further back in sixth and Italian Guido Migliozzi and Pablo Larrazábal at ten under.