GLASGOW (AFP) - Scottish football was plunged into mourning after Motherwell captain Phil O'Donnell died on Saturday after collapsing during his side's 5-3 win at home to Dundee United.

The 35-year-old midfielder, married with four children, was about to be replaced at Fir Park by substitute Marc Fitzpatrick near the end of the Scottish Premier League match when he fell to the ground.

Motherwell and Dundee United medical staff treated the player for five minutes on the pitch and continued to try to revive him en route to nearby Wishaw General Hospital, in the west of Scotland.

Despite the efforts of both clubs' medical staff and those at the hospital he did not regain consciousness and was subsequently pronounced dead.

Motherwell owner John Boyle told the club's website: "This is an unspeakable tragedy for Phil's family.

"At this stage we do not know the exact cause of death but the club is obviously liaising with the medical staff at Wishaw General.

"Everyone at Motherwell is shocked to the core and we are sure that everyone involved in Scottish football will feel the same.

"Phil was not only an inspirational player for Motherwell and club captain, but was an inspirational person.

"All of us at Motherwell are thinking of his wife Eileen and their four children."

Motherwell manager Mark McGhee added: "We are all totally devastated and our thoughts are with Phil's wife and family. Phil was a great professional and gave everything when he played the game. This is a shocking tragedy."

David Clarkson, O'Donnell's nephew, also plays for Motherwell and had scored twice in Saturday's match before being substituted after being alarmed at the sight of his uncle's collapse.

O'Donnell had started his career at Motherwell where he scored in their Scottish Cup victory over Dundee United in 1991.

He earned his one and only international cap for Scotland in 1993 against Switzerland before joining Celtic for a club record 1.75 million pounds.

Injuries curtailed his time with the Scottish giants and also cut short his stay with Sheffield Wednesday, where he moved in 1999.

After being released by the English club he returned to Motherwell in 2004 where he became captain and this season he'd helped the side climb to third in the table.

Gordon Smith, chief executive of the Scottish Football Association, led the tributes to O'Donnell.

He said: "This is absolutely devastating news. Phil was not just a wonderful footballer, he was a great human being. My thoughts are with his family at this tragic time."

And Peter Lawwell, the chief executive of Celtic, added: "When the news came through, everyone at the club was obviously shocked. Obviously our thoughts are with his family to whom we offer extreme condolences for a tragic loss of a young life. Everyone at Celtic Park will mourn him."

With O'Donnell's death the results from the other SPL games on Saturday paled into insignificance.

Celtic returned to the top of the table with a 3-0 win at home to Gretna - only hours after Rangers overtook them by winning 2-1 away to Hibernian.

Falkirk came from behind to win 2-1 at home to Hearts - who remain third bottom.

Inverness Caledonian Thistle won 3-1 at home to Kilmarnock and Stevie Lovell scored the only goal of the match as Aberdeen won 1-0 at St Mirren.