Scott McDonald proved he had no hangover from his midweek transfer disappointment as Motherwell eased into the Tennent's Scottish Cup quarter-finals.

McDonald had expressed "utter devastation" that an offer from Rangers was rejected by the Well board and received a mixed reception at the start of the fourth-round clash.

But the striker must have won over some detractors after having a hand in Brian Kerr's early opener, and he put the game beyond the Second Division leaders before the interval.

Morton - conquerors of Kilmarnock in the previous round - had decent spells of possession but lacked a cutting edge against a below-par home side.

Well brought back David Clarkson and Jim Paterson back from suspension after losing Richie Foran to Southend in midweek.

Morton recalled Kevin Finlayson for former Alloa midfielder Jamie Stevenson, who dropped to the bench.

Kick-off was delayed for 15 minutes as long queues of Morton fans waited outside Fir Park.

Well shaded the early possession but survived a scare when Chris Templeman was inches away from Kevin Finlayson's dangerous cross.

However, Kerr's first-time strike from the edge of the area found the top corner in the 10th minute after Darren Smith's volley had been blocked following a McDonald cross.

McDonald then almost connected with Smith's near-post cross but Well were struggling to retain possession.

Scott McLaughlin saw a powerful shot beaten away by Graeme Smith as Ton pushed forward.

David Clarkson headed straight at Paul Mathers at the other end but Morton held the territorial advantage.

The Greenock side had a great chance to level when Finlayson played through Paul McGowan.

But the on-loan Celtic striker's lob just cleared the post after Smith had rushed off his line and Well scored a second out of nothing seconds later.

The Well fans were chanting McDonald's name after he won the ball in the box, cut inside and fired under Paul Mathers for his 10th goal of the season in the 34th minute.

The Australian cap soon latched on to Smith's long kick-out and saw his lob just diverted by Mathers.

The goal knocked the stuffing out of the visitors who failed to trouble Smith again before half-time.

Morton came close three minutes after the restart when Templeman headed David McGregor's inswinging free-kick towards the back-post where Peter Weatherson just failed to turn it in.

At the other end Clarkson had a powerful shot from a tight angle held by Mathers after a long ball by Martyn Corrigan.

Stephen Craigan made a superb goalmouth interception from McGowan as Morton continued to probe.

McDonald had a chance to play Smith through on the break but elected to shoot from 25 yards, and the visiting defence blocked.

The lack of goalmouth action was evident when the home fans began a rendition of Flower of Scotland as the scoreboard relayed news of a Scottish lead at Twickenham.

McDonald's day did not go entirely to plan as he was booked for diving after falling over easily when McLaughlin brushed past him in the box.

Morton ran out of ideas as the game entered the final quarter and Well finally began to knock the ball around for spells without threatening Mathers.

Well went on to win the cup in 1991 the last time they knocked Morton out but they will need to step up a gear in the latter stages if they want a repeat.

Teams:

Motherwell Graeme Smith, Corrigan, Craigan, Reynolds, Murphy,Darren Lee Smith (McGarry 68), Kerr, Fitzpatrick, Paterson,McDonald, Clarkson (Keegan 82).

Subs Not Used: Meldrum, Quinn, Vadocz.

Booked: McDonald.

Goals: Kerr 10, McDonald 34.

Morton Mathers, Weatherson, Harding, Greacen, Macgregor,Finlayson, McGowan, McLaughlin, McAlistair,Templeman (Keenan 82), Millar (Stevenson 58).

Subs Not Used: McGurn, Walker, Russell.

Att: 9,394

Ref: J Underhill (Scotland).