John Millman’s fine end-of-season European campaign gathered more momentum when he battled past veteran Gilles Simon 7-5 6-7 (3-7) 6-2 to reach the quarter-finals of the Sofia Open.

The 31-year-old Queenslander Millman, fresh from his first ATP Tour triumph at the Astana Open at the start of the month, again demonstrated his buoyant form by prevailing against the Frenchman who, in typically doughty fashion, saved four match points before eventually capitulating.

Millman had to overcome the disappointment of seeing the never-say-die 35-year-old Simon save two of those match points before going on to snatch the marathon 82-minute second set in a tiebreak.

Yet the Australian brushed aside the setback to earn another break at the start of the third set and go on to set up a last-eight meeting with Canadian Vasek Pospisil.

There was more defiance from Simon who saved two more match points when 5-1 down in the third set but, at the fifth time of asking, Millman was not to be denied as he ran out winner after three hours and 18 minutes.