He will now face Lin's team-mate, the reigning Olympic and world singles champion Ma Long, tomorrow morning for a place in the final.

Boll, winner of the World Cup in 2002 and 2005, trailed 1-3 in sets and then 4-10 in the deciding game before fighting back.

He saved another match point at 10-11 before converting the first of his own to win 5-11, 11-13, 11-9, 9-11, 11-9, 14-12, 13-11.

“It was a crazy match and I had to fight because this is my living room," Boll said afterwards.

"I just felt I had to fight in this wonderful arena with the huge support from the fans and I was lucky as well. 

"I think I have to use the next 20 minutes to enjoy this victory."

The result was especially heartbreaking for Lin considering he lost from 10-5 up in the final set to fellow countryman Xu Xin at the last-16 stage of this year's World Championships.

Ma will now seek to repeat his 4-2 victory over Boll in the quarter-finals of the same event.

He beat Koki Niwa of Japan 13-11, 11-9, 11-5, 9-11, 11-8 in the quarter-finals today.

Ma did not participate in last year's World Cup but is seeking a third title after victories in 2012 and 2015.

Frenchman Simon Gauzy also excelled today in a seven-set thriller after ousting Olympic singles bronze medallist Jun Mizutani of Japan.

He led by a set on three occasions before eventually winning 11-7, 6-11, 13-11, 11-13, 11-9, 7-11, 11-8. 

Second seed Dimitrij Ovtcharov completed the European-heavy semi-final line-up after winning yet another match which went the distance against Alexander Shibaev of Russia.

The German trailed 0-2 before winning 9-11, 8-11, 12-10, 11-9, 11-7, 10-12, 11-7.

Both the semi-finals and the final are scheduled for tomorrow at the Country Hall De Liège.