Latvian sensation, Jelena Ostapenka has stunned world No.4 Simona Halep to claim her first Grand Slam crown.

Patty Mills has poured in 20 points in San Antonio's 110-107 overtime win over Houston on Wednesday (AEST) to give the Spurs a 3-2 series lead.

With Tony Parker injured, Mills earned a spot in Gregg Popovich's starting five and started off brilliantly, knocking down two three-pointers and dishing off two assists in the opening half of the first quarter.

MVP candidate Kawhi Leonard dropped 22 points and collected 15 rebounds in the win, however, failed to play in the overtime period after rolling his ankle. His status remains unknown for game six.

Veteran Manu Ginobli provided a big boost for the home side with 12 points, seven rebounds and five assists off the bench, including a rim-rattling dunk in the second quarter.

The 39-year-old also came up big in the clutch, including a big triple and lay up late in the fourth quarter, before blocking James Harden's potentially game-tying three as time expired in overtime.

Houston had just seven players enter the court on Wednesday, with Harden's triple double (33-10-10) not enough to steal the game away from the playoff-hardened Spurs.

Patrick Beverley had 20 points including 5-7 from deep while Ryan Anderson had 19 points and seven rebounds in the loss.

The series shifts back to Houston on Friday in a win or go home situation for the Rockets.