"He was a man amongst boys," said Motherwell manager Mark McGhee, "in every sense of the word, in his attitude and professionalism, in his integrity and in his sincerity."
The 35-year-old O'Donnell was just about to be replaced when he collapsed with 12 minutes left in Motherwell's game with Dundee United and never gained consciousness. Efforts to revive him failed as he was taken by an ambulance to a local hospital, where he was pronounced dead.
O'Donnell's nephew, David Clarkson, had scored two goals in the match for Motherwell and was substituted shortly after O'Donnell had collapsed. The game ended in a 5-3 victory for Motherwell, third in the SPL.
The 35-year-old O'Donnell's career included stints at Celtic and Sheffield Wednesday in England, but he is best known for his play during two stints at Motherwell. He was 19 when he scored for Motherwell in its 4-3 win over Dundee United in the 1991 Scottish Cup final, the last major trophy the club has won.
O'Donnell, twice named Scottish PFA Young Player of the Year, was Motherwell's most expensive transfer when he joined Celtic in 1994, a year after he made his first and only appearance for Scotland.
Injuries limited O'Donnell to only 20 appearances in four seasons at Sheffield Wednesday, and he returned to Scotland in 2004. Dundee United was also the opponent for his first game back at Motherwell, a 3-1 win that featured a hat trick by Clarkson.
"But for the injuries he would have had may more caps," former Scotland manager Craig Brown told Sky Sports. "It's very, very sad news and I just can't take it in. He was a perfect gentleman. You will not get a more ideal role model for a young footballer than Phil O'Donnell."
RECENT DEATHS. O'Donnell, who is survived by his wife, Eileen, and their four children, was the third professional player to die in a game in the last four months.
Sevilla midfielder Antonio Puerta died on Aug. 28, three days after collapsing during a La Liga match against Getafe. The next day Zambian striker Chaswe Nsofwa of Israeli Second Division club Hapoel Be'er Sheva collapsed and died during a practice match in the Negev Desert city of Be'er Sheva.