The Canadian Fed Cup team became a major underdog in its tie against Switzerland when reigning U.S. Open champion Bianca Andreescu was not included in the singles matches at Thursday's draw ceremony.

Andreescu has not played a competitive match since suffering a left knee injury at the WTA Finals over three months ago.

"We had to make a tough decision," Canadian captain Heidi El Tabakh said at a team availability. "It had to be a last-minute decision. With Bianca's injury, we are just taking it day by day. Time was against us this time, but we weren't going to have her play singles unless she was 100 per cent or close to 100 per cent.

"She's not quite there yet, she's close. So we just don't want to take our chances and have a big setback."

Andreescu, the world No. 6 from Mississauga, Ont., was scheduled to play doubles with Ottawa's Gabriela Dabrowski if the best-of-five tie goes the distance. Teams can substitute players up to an hour before the match although El Tabakh ruled out any changes to her singles lineup.

The Swiss side is anchored by fifth-ranked Belinda Bencic, who will play 267th-ranked Eugenie Bouchard of Westmount, Que., on Friday. Teenager Leylah Annie Fernandez of Laval, Que., the world No. 185, will open the tie against No. 68 Jil Teichmann.

"We have a great team, we have a great lineup," El Tabakh said. "Leylah is a young and upcoming player and fearless on the court. She already played her first Fed Cup tie last year against the Czech Republic so she's had that experience.

"Genie plays her best tennis at Fed Cup. She plays her best tennis and is very tough to beat. So I'm very confident in my decision and it had to be done."

Reverse singles go Saturday, followed by the doubles match.

"It'll be really tough," Bouchard said. "Obviously Switzerland are the favourites as they have girls that are much higher ranked than us that are playing tomorrow. But I believe in our team and we have to go in with the underdog mentality and try to fight, do anything that we can to win on the court."

WATCH | Andreescu injures knee at WTA Finals:

Bianca Andreescu of Mississauga, Ont., injured her left knee while returning a serve in her WTA Finals match against Karolina Pliskova of the Czech Republic. Andreescu would later retire from the match. 1:50

The Canada-Switzerland winner advances to the inaugural Fed Cup Finals in Budapest in April. The losing team will fall into a playoff tie in April against a Regional Group I nation for a chance to reach the 2021 qualifiers.

Andreescu has declined to offer specifics on the severity of her knee injury. She wasn't asked about it at Thursday's availability.

"Well I don't need surgery so I wouldn't say it's very bad," she told The Canadian Press in December. "I can't really say much about it. I'm just trying to rehab as much as possible and stay as positive as I can."

Andreescu twisted her knee when she stretched to make a forehand return during a match in late October. She said at the time that she "heard a crack," and eventually withdrew from the season-ending competition after getting results from an MRI exam.

She resumed on-court training in December and has met with Dr. Angel Ruiz Cotorro, who has helped Spanish star Rafael Nadal with knee issues in recent years.