O'Donnell, one of Lasley's predecessors as Well skipper, died of heart failure exactly six years before Motherwell's emphatic Scottish Premiership victory at Firhill.
That day, Lasley came onto the park during Motherwell's win over Dundee United just as his friend, O'Donnell, the former Scotland midfielder, was being carried off on a stretcher, so no-one had to remind him of the anniversary.
But a round of applause near the 10th minute of the game helped show how much esteem O'Donnell was held in.
The Thistle fans showed their class by joining in with the applause, which came just after former Motherwell winger Steven Lawless had opened the scoring for the Jags.
Lasley, who equalised for Motherwell in the 15th minute, said: "It was terrific. I would echo the sentiments of the fans.
"I would dedicate that win to Phil. He will never be out of our thoughts.
"On this day, our thoughts are with his family. It was a poignant moment. I heard it myself during the match and it was certainly a nice touch. I'm just glad we could get the win to go with it.
"When you look at social media, you realise how many people he touched, throughout the whole of world football.
"People that knew him realised how good a guy he was. Take away the football - he was just a real good guy and a true gent.
"He was somebody that I was privileged to be a team-mate of and somebody I could call a friend."