The teams will play for the Sean Graham Memorial Trophy, in memory of massive Maryhill fan Sean who passed away in January, with McGrain presenting the trophy to the winners.
McGrain, 62 times capped for Scotland, spent two seasons on loan at Maryhill from Celtic from 1966 to 1968.
Before the match there will also be a tribute to former Maryhill committee member, and Jags fan, Grant Clark who also died earlier this year.
Among the players line up for the Thistle Legends squad are current boss Ian McCall and his assistant Alan Archibald, Clyde boss Danny Lennon, Simon Donnelly, Kenny Arthur, David Rowson, Gerry Britton, Marc Twaddle, Martin Hardie and David Irons.
And the Maryhill line-up will include Lochburn favourites Maryhill team will include Martin Nelson, Terry Farrell, Andy McClay, John Sherry, Stevie Campbell, Bryan Dingwall, Ally Grant, John Mitchell, Scott McHarg, Tom McAllister, Craig Ferguson, Billy McCormack
The day's entertainment will also include face painting, crossbar challenge and a penalty competition and admission is £6 for adults and £3 concessions.
It gets under way at 1.30pm with the match kicking off at 2pm.
There’s also action at Lochburn Park on Saturday when Maryhill’s current side take on West of Scotland League Conference A rivals Arthurlie in the first round of the South Challenge Cup.