Connacht have been hit with their first positive case of Covid-19, which has ruled out four players from their squad to take on Racing 92 on Sunday.
The province said that one player and three others deemed close contacts were ruled out of contention.
"Those close contacts and all other players and management underwent a second round of PCR testing yesterday and produced no further positive results," said the province in a statement.
Andy Friend is able to welcome back a number of Ireland internationals for the game against last season's beaten finalists in Paris (3.15pm Irish time).
Dave Heffernan, Finlay Bealham and Kieran Marmion have all been named in the starting line-up, as well as Ultan Dillane.
Heffernan and Bealham are joined by Denis Buckley in the front row, while Dillane is partnered by Eoghan Masterson to complete the tight five.
Jarrad Butler captains the side from openside flanker in a back row that also includes Sean Masterson and Paul Boyle.
Jack Carty starts at out-half, while Tom Daly and Sammy Arnold continue to pair-up at centre.
In the back three Matt Healy comes on to the wing while Alex Wootton and John Porch are both retained after impressive starts to the season for the duo.
There’s also a return to the matchday squad for Tiernan O’Halloran, with the Clifden native recovering from injury to be named among the replacements.
Friend said: "Unfortunately, we have been slightly disrupted by a positive case within our bubble, but we appreciate this is the world we are living in right now.
"I've said from the start that the team that adapts the most will be the team to succeed, and we have adapted accordingly.
"There’s arguably no bigger challenge in European rugby than what we’ve got this weekend, but it’s one we’re absolutely relishing.
"They’re full of talent across the field in an impressive stadium, but in the end of the day we must back ourselves from the get-go and fully believe we can get a result.
"If we do that and bring the level of energy and physicality that I know we’re capable of, then the result will take care of itself."
Meanwhile, former Ireland and Munster players Donnacha Ryan and Simon Zebo have been named on the bench for Racing.
Connacht: John Porch, Alex Wootton, Sammy Arnold, Tom Daly, Matt Healy, Jack Carty, Kieran Marmion; Denis Buckley, Dave Heffernan, Finlay Bealham, Eoghan Masterson, Ultan Dillane, Sean Masterson, Jarrad Butler (capt), Paul Boyle.
Replacements: Shane Delahunt, Jordan Duggan, Jack Aungier, Cian Prendergast, Conor Oliver, Caolin Blade, Bundee Aki, Tiernan O'Halloran.
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