Connacht head coach Stuart Lancaster has included both players for the clash with RC Vannes (kick-off 7pm local time/6pm Irish time), which comes four weeks out from the start of the BKT United Rugby Championship.
Featuring on the left wing tomorrow night, Mack Hansen has been out of action since last December when he underwent surgery on a troublesome foot injury.
The 28-year-old played for Ireland the previous month against Australia and South Africa in the Quilter Nations Series, while his last appearance for Connacht was against the Vodacom Bulls in mid-October.
Byron Ralston also last lined out for the province in October, his impressive two-try performance away to Munster unfortunately marred by a season-ending ACL injury.
He will return against Vannes, last year's Pro D2 champions, in a centre partnership with John Devine, while the westerners' back-line will be led by Josh Ioane and Colm Reilly.
"Really looking forward to the game against Vannes," said Lancaster. "I think it's a better game for us in that they are a week away from playing Top 14. It's a sell-out in their home stadium.
"They didn't lose a game there last year, so it is a big challenge, it's a proper game. We've got 32 lads here, 28 in our matchday squad, and I'll look to get all 28 on at some point.
"But we're treating it as a proper game. You know, we've previewed them, we have a plan, etc, etc. We'll see where we are after this game, with Ealing to come."
He added: "There is nothing that beats an away trip, be it a two-day one, but in this instance, Vannes were very good, very accommodating in allowing us to train in their facility so we could have that extended time over here.
"We arrived on Monday evening, so Tuesday, Wednesday, training at their facility. We're going out for a meal with their coaching team this evening just to share ideas, and obviously we play the game tomorrow night.
"Equally it's great for us as coaches and management to spend time together, but also the players to have that non-training time just to build the connections."
Fiachna Barrett will pack down at tighthead prop, fresh from joining Connacht's senior squad this summer as an Academy graduate.
The pre-season encounter at Stade de la Rabine will see Paul Boyle and Seán O'Brien combine in the back row with Shamus Hurley-Langton, who ended last season with seven tries in eight games.
The extended bench has new signings Jerry Cahir and Thomas Connolly covering the prop positions, and two members of the Ireland Under-20s' 2026 World Rugby Junior World Championship squad, backs Seán Walsh and Daniel Ryan.
Walsh and Ryan are two of six Academy players included, along with David Walsh, Max Flynn, Bobby Power, and Albert Lindner, the Frankfurt-born scrum half who made his Connacht debut against Montpellier last January.
Lancaster's charges arrived on the French west coast on Monday, and have used the opportunity to continue preparations for their URC opener at home to the DHL Stormers on Friday, September 25.
Before that, Connacht will have a second pre-season game against Ealing Trailfinders at Dexcom Stadium on Saturday week (kick-off 5pm). Tickets are on sale online here.
CONNACHT (v RC Vannes): Sam Gilbert; Shane Jennings, John Devine, Byron Ralston, Mack Hansen; Josh Ioane, Colm Reilly; Jordan Duggan, Eoin de Buitléar, Fiachna Barrett, Niall Murray, David O'Connor, Seán O'Brien, Shamus Hurley-Langton, Paul Boyle.
Replacements (from): Dylan Tierney-Martin, Jerry Cahir, Thomas Connolly, David Walsh, Max Flynn, Bobby Power, Ben Murphy, Seán Naughton, Seán Walsh, Harry West, Finn Treacy, Daniel Ryan, Albert Lindner.
