In-form Morton beat Motherwell 2-1 in the Scottish Gas Scottish Cup fifth round at Cappielow after Robbie Muirhead’s first-half corner caused chaos in the visiting defence.
Muirhead’s inswinging corner caught out Liam Kelly, who palmed the ball out but saw it ricochet over the line off team-mate Harry Paton.
The home side had used their wind advantage to good effect in the first half and kept Motherwell under pressure while the Steelmen struggled to offer any real attacking threat.
George Oakley doubled Morton’s lead after the break and Motherwell’s comeback attempts were too little, too late.
Substitute Jack Vale pulled one back with a deflected effort in the 85th minute but Dougie Imrie’s side deservedly held on to become the first club in the quarter-finals.
The draw for the fifth round of the Scottish Cup will take place on Sunday evening.
The ties will be played the weekend of March 9/10.