The Austrian made a bright start, winning 10 out of the first 11 points to surge into an early 3-0 lead before losing his concentration in spectacular fashion.
Goffin, though, hit a golden streak of his own, included taking an astonishing 15 points in a row.
Thiem was showing signs of a lack of confidence and a ninth error from his racket handed the Belgian the lead. Goffin nailed a stunning forehand winner down the line to complete a remarkable turnaround in fortunes in a baffling set.
Fourth-seeded Thiem, who went the distance in his two group matched against Grigor Dimitrov and Pablo Carreno Busta, continued to struggle with fatigue playing a major factor.
Goffin took advantage of his opponent’s self-inflicted collapse with a double break in the second set and it wasn’t long before he wrapped up victory in 71 minutes to set up a date with six-time winner Federer on Saturday afternoon.
Shot of the match
Goffin ready for Fed-Express
“It was a pity to play Dominic for a place in the semi-finals. He’s such a good friend, but I had to stay calm and be ready for a tough battle,” said Goffin, who became the first man ever from Belgium to reach the semi-finals of the tournament.
“I needed to be 110 per cent on the court to be ready for all my opponents. I hope I can do the same in the semi-finals. I played Roger so many times and it’s always a tough match. I have nothing to lose so I will try to raise my level.”
The good news for Goffin is that the match didn’t test him at all. The way he’s striking the ball gives him a real chance against Federer.
Goffin will face six-time champion Roger Federer in the semi-finals on Saturday afternoon. The Swiss world No 2 leads the head-to-head record 6-0. You can watch both semi-finals live on Sky Sports, with the action getting underway from midday.