When Fasth failed to make birdie at the 18th after play resumed, Montgomerie had his first win in 19 months. He won by a single shot, marking the eight-time Order of Merit champion's 31st career European Tour victory.
'After nearly two years of a dry spell it's great to be back,' Montgomerie said. 'You wonder if it's ever going to happen again.'
It nearly happened again last weekend when Montgomerie finished runner-up to surprise winner Pablo Larrazabal at the Open de France. Monty ended four shots back in second place, his best finish since his win at last year's European Open.
Montgomerie and Fasth will be in the field this week at The London Golf Club, but Larrazabal will not. The field also features reigning Players Championship winner Sergio Garcia, reigning Order of Merit champion Justin Rose and reigning British Open winner Padraig Harrington.
The GOLF CHANNEL will have coverage of all four rounds this week.
Next week is the Scottish Open, where Gregory Havret won last year.