Thomas missed out on the Scarlets 31-16 defeat to Ulster in Belfast on Saturday and is the only change in head coach Phil Davies' line-up.
Scotland lock Scott Macleod joins teenager Lou Reed in the second-row and former New Zealand Maori prop Deacon Manu is added to the replacements bench after missing out on the trip to Belfast with a back injury.
Director of Rugby Phil Davies is in confident mood for the visit of Glasgow despite an opening day defeat to defending champions Ulster.
"It was obviously disappointing to lose against Ulster but there were plenty of positives to come from the game. We had a few young guys in the team and they all put their hands up.
"We've got an exciting backline brimming with talent and Glasgow like to play ant open expansive game so it should be an exciting game."
The Warriors will be looking to bounce back from their last-minute 24-23 defeat to Newport-Gwent Dragons at Hughenden last Friday.
Head coach Sean Lineen has made three changes to his starting line up from the team who narrowly lost to the Dragons last week.
In the backs, Colin Shaw replaces Mike Robert on the left wing and in the forwards, John Beattie replaces the injured Jon Petrie and Andrew Wilson replaces John Barclay.
"It's an understatement to say that it was a massive disappointment last week," said Lineen.
"However, we've got to take on board that it's a long season, put it behind us and look forward with a positive attitude and belief in the squad."
Scarlets: M Thomas, D James, R King, G Evans, D Daniel, S Jones, D Peel (capt), I Thomas, M Rees, J Davies, L Reed, S Macleod, I Afeaki, G Thomas, N Thomas
Subs: D Manu, K Owens, A Jones, A Popham, C Stuart Smith, C Thomas, M Watkins.
Glasgow Warriors: Francisco Leonelli; Thom Evans, Graeme Morrison, Andy Henderson, Colin Shaw; Dan Parks, Sam Pinder; Justin Va'a, Fergus Thomson, Euan Murray, Andy Newman, Alastair Kellock (capt), Andrew Wilson, John Beattie, Donnie Macfadyen.
Replacements: Eric Milligan, Kevin Tkachuk, Dan Turner, Stevie Swindall, John Barclay, Colin Gregor, Hefin O'Hare, Sean Marsden