Last year's top try scorer DTH van der Merwe, meanwhile, is in line for his first Warriors action of the season.
The Canada wing/centre hasn't played since the Rugby World Cup because of a shoulder injury, but has progressed well under the care of the Warriors medical team and will be among the substitutes at the Stadio di Monigo.
The Glasgow starting XV shows five changes from last Saturday's 35-29 defeat away to Munster. Morrison comes in at inside centre, with hat-trick hero Stuart Hogg moving to the familiar surroundings of full-back.
The other switches in the backline see Tommy Seymour replace Federico Aramburu on the wing, and Duncan Weir resume stand-off duties. The 20-year-old scored all of the Warriors' points and was named RaboDirect Man of the Match in the last venture to Italy, an 18-6 win over Aironi back in November.
Up front, Ryan Grant, one of the club's most consistent performers, lines up at loose-head prop. Jon Welsh, who wore the number 1 jersey in Cork, hurt a shoulder in training this week and is thus unavailable for the Treviso clash. Loose-head bench cover will be provided by Gordon Reid.
The other change to the pack comes at No.8, where Barclay gets the nod over Johnnie Beattie, having performed well in the middle of the back row in the pre-RBS 6 Nations period.
Head coach Sean Lineen told www.glasgowwarriors.org: "It's absolutely fantastic to have three guys like Graeme, John and DTH coming back into the 23 for what is the biggest game of our season so far.
"They're hugely influential both on and off the field, and for DTH in particular, this is a reward for a lot of hard work put in alongside the Warriors medical team.
"DTH is a quality player who can bring that little bit of inspiration to a game. It's great he's made it back to play his part in what we're all determined will be a successful finish to the season.
"In terms of the other changes, Tommy Seymour showed up really well off the bench against Munster and is chomping at the bit to start.
"Federico has been in great form, but he'll benefit from a break, while at stand-off we're in the really positive position of being able to pick from two strong options in Duncan and Ruaridh [Jackson].
"We always planned to start Ryan Grant in this game because of the level of performance he's delivered across the campaign, and although it's disappointing for Welshy to miss out, we've got a very capable replacement there in the shape of Gordon Reid.
"Once again, we're looking for a high-energy, accurate display from all 23 players. We're putting our season on the line in this match, and the players are certainly in the mood to deliver."
The Warriors are assured of some vocal support in the Stadio di Monigo, with a 35-strong group from Greenock Wanderers heading to Italy.
The Fort Matilda crew are playing local side Paese RFC (based only 5km away from Treviso) on Saturday evening, before heading to the Glasgow match on the Sunday.
The Warriors have provided the group with an allocation of complimentary tickets as a thank you for their support.
Fans unable to make the trip are invited to a special screening of BBC ALBA's live coverage at Waxy O'Connor's, 44 George Street, Glasgow.
Warriors players will be in attendance to take in the action with supporters, with the match being shown in the Guinness and Church areas on the basement level of the city centre bar
GLASGOW WARRIORS TEAM TO PLAY BENETTON TREVISO IN THE RABODIRECT PRO12 AT STADIO DI MONIGO ON SUNDAY 22 APRIL (KICK-OFF 3.05PM LOCAL TIME (2.05PM UK TIME), LIVE ON BBC ALBA)
15 Stuart Hogg
14 Tommy Seymour
13 Alex Dunbar
12 Graeme Morrison
11 Colin Shaw
10 Duncan Weir
9 Chris Cusiter
1 Ryan Grant
2 Pat MacArthur
3 Mike Cusack
4 Richie Gray
5 Al Kellock (CAPTAIN)
6 Rob Harley
7 Chris Fusaro
8 John Barclay
SUBSTITUTES
16 Finlay Gillies
17 Gordon Reid
18 Moray Low
19 Tom Ryder
20 Johnnie Beattie
21 Henry Pyrgos
22 Ruaridh Jackson
23 DTH van der Merwe
Not considered for selection due to injury: Rob Dewey (shoulder), Rory Lamont (leg), David Lemi (hand), Fergus Thomson (shoulder), Ryan Wilson (knee), Jon Welsh (shoulder).
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