Mann started the United Rugby Championship (URC) impressively for Cardiff after starting both summer Tests in Japan at blind-side.
Now he moves across for a first international start at open-side after playing there just twice in the URC last season.
There are question marks over Mann’s suitability to play at blind-side against the heavy-hitters but the 6ft 3ins, 16st 2lb forward undoubtedly has attractive attributes.
“He’s got flexibility in how he plays,” said Tandy, a combative flanker in his playing days.
“He has athletic ability, ball-playing skills but also his energy levels with how he gets off the line in defence.
“He gets people to the floor, he’s a jackal threat and has line-out ability. He is an all-round player who can play across the back row.”
Mann has worn six on his back six times in international rugby to go along with a pair of appearances off the bench.
“It’s just a number, whatever the coaches ask of me I make sure I give 100% so it doesn’t matter to me,” said the 23-year-old from Aberdare.
Wales might not replace Morgan but the starting trio – plus replacements Freddie Thomas and Taine Plumtree – aim to soften the blow.