Gregor Townsend spoke of "a tough week for world rugby" as Glasgow Warriors prepare to face Munster following the death of Anthony Foley.
The Irish side's head coach died aged 42 at the team hotel in Paris last Saturday night before the scheduled game against Racing 92 the following day, which was postponed.
Foley's funeral will be held in County Clare on Friday.
Tournament organisers have confirmed that Munster's European Champions Cup pool game with the Warriors in Limerick will go ahead on Saturday.
Glasgow's head coach Townsend first came across Foley when they faced each other as schoolboys and he paid tribute to the former back row forward who played 62 times for Ireland.
"It has been a tough week for world rugby," said the former Scotland player.
"You saw the reaction from all over the world, not just in rugby but in sport.
"It is such a loss for our game, a huge loss for Munster rugby so our thoughts go with them and Anthony's family.
"Munster was probably the team that shaped the Champions Cup for what it is today.
"Winning away from home, winning in France, getting to finals, winning big games in those finals and having huge travelling support.
"In that period I was fortunate enough, I was playing for Castres and I think we played Munster five times over two seasons and Anthony was a key player for them.
"We played against each other a number of times.
"I think we played each other in the schoolboy teams a long time ago, the Munster games and Ireland.
"He was aggressive and intelligent too. A really good modern number eight with a great ball-carrying side to his game.
"I was looking forward to catching up with him. He was always very good after games whether Munster won or we won.
"As I got to know him more as coaches he would always come up and chat with you and be honest and share what was going on in his world as a coach."
A French coroner said on Tuesday that Foley died due to a heart condition which led to a build-up of fluid in his lungs.
Townsend knows there will be a lot of emotion at Thomond Park on Saturday.
A minute's silence or minute's applause for Anthony Foley will be observed at all Round 2 matches in the Champions Cup and the Challenge Cup pic.twitter.com/ti96dW2tNF— PA Sport (@pasport) October 19, 2016
"I think it is a game to remember what Anthony did and help create at Munster," he said.
"He was one of the key players that got them that success and he was also a very good coach.
"We always knew it was going to be a huge occasion. Munster in the Champions Cup are a different team. They play at a much more intense level.
"I would imagine it would be a huge game in terms of crowd support.
"Our players appreciate the enormity of what has happened and being involved in the game will hopefully bring out the best in both teams."