David Clarkson's double sealed victory for Motherwell in the Clydesdale Bank Premier League, moving the third-placed side four points clear of their nearest rivals Dundee United.

Clarkson and Chris Porter found the net in the opening nine minutes, and although Don Cowie soon reduced the deficit for the Highland visitors, Clarkson made it 3-1 with a sweetly-struck volley just before the interval.

There were no further goals after the break, although Porter and Grant Munro, twice, hit the bar.

Keith Lasley came into Motherwell's midfield line-up in the only change from their 3-1 weekend win over Gretna, replacing knee injury victim Stephen Hughes.

Inverness manager Craig Brewster, who had said he would make changes to his team to adapt to the condition of the Fir Park pitch, brought in Graham Bayne and Dennis Wyness in place of the benched Ian Black and Marius Niculae, who dropped out of the squad.

Motherwell took a seventh-minute lead when Ross McCormack sent a crossfield pass to Clarkson on the right side of the box, and he lashed his effort into the roof of the net.

The Fir Park side doubled their lead less than three minutes later - McCormack laid the ball back to the left corner of the penalty area for the arriving Stevie Hammell, and he crossed to the far post where Porter sent a powerful downward header bouncing emphatically across the line.

Inverness had rarely threatened in the opening quarter, but reduced the deficit from their first real foray towards Graeme Smith's goal.

Don Cowie seemed to have been forced away from the danger area, but the ball broke to him 20 yards out and he sent an unstoppable shot sailing high into the roof of the net.

The visiting defence gifted Motherwell a real scoring chance on 25 minutes.

Hammell's corner from the right in a crowded box was only cleared as far as Clarkson, who ran back towards goal and unleashed a shot which Fraser to tipped around round the post.

Motherwell enjoyed the majority of the play and continued to press the Inverness goal,.

Darren Smith got the ball caught under his feet as he tried to turn and shoot four minutes from the break, with Phil McGuire having to head Clarkson's follow-up out for a corner on the left.

And the hosts scored their third goal from this set-piece.

Hammell's flag-kick was headed out as far as Clarkson on the edge of the box - and he hit an impressive left-foot volley which flew past Fraser.

Porter nearly doubled the hosts' lead 30 seconds into the second half when he burst down the left and unleashed a diagonal effort which hit the underside of the bar, and bounced down into Fraser's arms without crossing the line.

The same fate befell Grant Munro's close-range header three minutes later, which was cleared off the line by Hammell.

And the unfortunate Inverness defender saw another header strike the bar shortly afterwards when a corner was cleared to him on the right side of the area.

Russell Duncan sent a quickly-taken free-kick into the arms of home goalkeeper Smith, but the next real effort on goal came in the 68th minute when McCormack launched a free-kick from the left wing into the box after being fouled by Ross Tokely, and Fraser won by a split second as he and Clarkson jumped for the ball at the far post.

Fraser had the visiting fans' hearts in their mouths in the 72nd minute when he rushed outside his area for a clearance, but managed to sidefoot it to Munro before McCormack rushed in to take advantage.

The match was held up for a few minutes with a quarter of an hour to go to allow a change of referee, with the injured John Underhill being replaced by fourth official Frank McDermott.

McDermott waved away Inverness' calls for a penalty five minutes from time when Russell Duncan looked to have been fouled by Lasley just inside the box.

Motherwell went down the other end, with Porter heading narrowly wide of the right-hand post, before Inverness closed the game with a Cowie free-kick which went over.

Teams:

Motherwell Graeme Smith, Quinn, Craigan, Reynolds, Hammell, Darren Smith (Lappin 53), Lasley, Fitzpatrick, Clarkson, McCormack (Maguire 73), Porter (Jamie Murphy 89).

Subs Not Used: Daniels, Brian McLean, Danny Murphy, Archdeacon.

Goals: Clarkson 7, Porter 10, Clarkson 42.

Inverness CT Fraser, Tokely, Munro, Hastings, McGuire, Duncan, McBain (Paatelainen 76), Imrie (Black 76), Cowie, Wyness, Bayne.

Subs Not Used: Malkowski, Watt, McAllister, Kerr, Vigurs.

Booked: McGuire, Wyness.

Goals: Cowie 19.

Att: 4,526

Ref: John Underhill (Scotland).