Last updated on .From the section Scottish Championship

Kalvin Orsi's diving header gave Morton an early lead at Tannadice

Greenock Morton were denied a shock win at Tannadice by Lawrence Shankland's last-minute equaliser as Dundee United extended their lead at the top of the Scottish Championship to 18 points.

United were facing a first defeat in 14 matches until the Scotland striker headed home a Liam Smith delivery for his 26th club goal of the season.

The home side had the ball in the net after only 32 seconds but Osman Sow was judged offside, and they fell behind in 17 minutes when Kalvin Orsi met Nicky Cadden's cross with a diving header.

Jack Baird's goalline clearance denied Shankland an equaliser and Sow and Peter Pawlett also came close before Morton were finally breached.

Second-place Inverness Caledonian Thistle's defeat at Ayr United means the Tannadice men increased their advantage at the summit, while Morton move up a place to seventh.

David Hopkin's side have lost just one of their last five league games and are three points adrift of the top four and two clear of the bottom two.

Dundee United manager Robbie Neilson: "Losing the early goal made it difficult for us because it gave Morton something to hang on to and they defended very well. I was really pleased we continued to move the ball and get into good areas and eventually got what we deserved."

Morton manager David Hopkin: "We should have had three points but I would have taken one before the game. We always knew they would get a chance and it fell to the wrong person. I don't think Lawrence has had a chance all game and we defended magnificently as a team. He looked a bit offside."