After starting the year 2019 outside top 100 of ATP rankings, Auger-Aliassime reached the final in Rio de Janeiro and Lyon but lost both. At Stuttgart, the Canadian will look to win his first title of the year.
Raonic wished Auger-Aliassime the best for the final but said it was hard for him to accept the situation he was in.
"It's hard for me to accept this situation but it is how it is. I'm very sorry and apologetic that I'm unable to compete today. I was hoping for the best after my match yesterday.
"But I'm happy that Felix has an opportunity to win his first title, so I wish him all the best," Raonic said.
🗣 @milosraonic: "It's hard for me to accept this situation but it is how it is.— Tennis TV (@TennisTV) June 15, 2019
"But I'm happy that Felix has an opportunity to win his first title, so I wish him all the best." 🙏🇨🇦#MercedesCup @felixtennis pic.twitter.com/ofKe9qtO9b
Auger-Aliassime will be facing the in-form Matteo Berrettini in the final on Sunday after the Italian beat Germany's Jan-Lennard Struff 6-4, 7-5 to reach his first ATP final on grass.
The 18-year-old Canadian said it wasn't a good look to see Raonic having to withdraw but acknowledged the "unbelievable" week of tennis he has had so far.
"It's just tough to see Milos having to withdraw. He's one of the best guys on Tour.
"It's been an unbelievable week for me. I've been playing good tennis. I got through on the edge yesterday and to be in another final, it's unbelievable. So I think I'll try to enjoy it and give everything also because it's obviously my third final this year, so I'll try to give it my all to maybe get my first title."
Berrettini, on the other hand, has been having the week of his life. After defeating Nick Kyrgios and Karen Khachanov in the first two rounds, Berrettini is now looking to win his first trophy in Germany.
"I'm really looking forward to seeing what's going to happen. I never played him (Auger-Aliassime), I just practised once [with him] here for the first time. I think it's going to be a great game and I'll try to do my best," Berrettini said.
In some good news for India, Rohan Bopanna and Denis Shapovalov reached the final of men's doubles after registering a 6-3, 6-4 win over Nick Kyrgios and Matt Reid.
They will take on top seeds Bruno Soares and John Peers in the final.