The 24-year-old takes charge of a starting XV showing 12 changes from last weekend's bonus-point victory over the DHL Stormers at Scotstoun, as Franco Smith's side go in search of a victory that would secure them a place in the last 16 of the competition.
Lucio Sordoni is the sole survivor of the front-row that got the better of the Stormers, as the Argentinian tight-head is joined by Nathan McBeth - making his first start for the club - and Johnny Matthews at the coal face.
Richie Gray returns to the side after missing last weekend's win at Scotstoun, joining JP du Preez in the second-row - the tallest-ever starting combination fielded in the professional history of Glasgow Warriors.
Sam Johnson returns from injury to start at inside centre, joining captain McDowall in the midfield for his first outing in almost three months.
Similarly, Cole Forbes's recovery from a neck injury sees the winger included in a matchday squad for the first time since October's visit to the Cell C Sharks, coming into a back three completed by Ollie Smith and Josh McKay.
Tom Gordon completes the contingent of forwards, the openside having recovered from a calf injury sustained during the trip to South Africa in October.
Speaking following selection, Head Coach Smith told glasgowwarriors.org: "Tomorrow is another important step in our development as a squad.
"Whilst we've been on a strong run of recent form, we know that there are still areas in which we can improve and it's important for us to take our lessons while we're winning.
"We're also pleased to give Stafford the chance to captain this group for the first time. He is a player who has shown his leadership qualities both on and off the field across this season, and is someone to whom I know this honour means a great deal."
15 Josh McKay
Unavailable for selection: Fraser Brown (head), Gregor Brown (foot), Scott Cummings (foot), Rory Darge (ankle), Zander Fagerson (hamstring), Oli Kebble (shoulder), Sintu Manjezi (knee), Jack Mann (head), Enrique Pieretto (chest), Ross Thompson (ankle), Murphy Walker (neck), Ryan Wilson (knee)