That means Canada's most decorated downhiller won't race the season-opening downhill or super-G on Nov. 29-30 in Lake Louise, Alta., nor will he compete the following week in Beaver Creek, Colo.
"Lake Louise is definitely a scratch this year," Guay said Tuesday from Toronto.
"Right now, our optimistic calculations should put me back on snow around the seventh of December. If everything goes well from there, I'd like to start racing the last weekend of December."
The 33-year-old from Mont-Tremblant, Que., had surgery to replace cartilage and bone in his left knee in June. Guay underwent arthroscopic surgery on the same knee in March.
"So far it's been healing well," Guay said. "It took a little bit longer than originally anticipated, but things are on schedule now. I'm working on gaining some mass and strength back into my leg."
Guay won the men's world downhill championship in 2011 after claiming the World Cup overall title in super-G in 2010. Last season, he passed Steve Podborski for the most career World Cup medals won by a Canadian and now sits at 22.
After finishing off the podium at the 2006 and 2010 Winter Games in fourth and fifth respectively, Guay really wanted to win some Olympic hardware last February in Sochi, Russia.
But he twisted his left knee in January while training in Wengen, Switzerland, and arrived in Sochi hobbling. He'd also had surgery on that knee in 2013.
Guay was 10th in the downhill in Sochi and was disqualified in the super-G for missing a gate. His Canadian teammate Jan Hudec tied for bronze in the super-G to claim Canada's first alpine Olympic medal since 1994.
"It's not easy, certainly," Guay said. "You work for this for four years and knowing I was competitive early on in the season makes it that much more frustrating. I knew going in my knee was a problem and it wasn't 100 per cent. It weighs on you. When you go into a race, and confidence is such a huge thing, and you know your knee isn't performing the way you'd like it to, it's not an easy thing.
"I personally struggle with that. I'm not the kind of guy who can put things aside. Jan Hudec's extremely good at that. If he's racing through pain, he's able to do that extremely well, whereas I struggle with that a little bit more."
The pursuit of that elusive Olympic medal will keep Guay racing to a fourth Winter Olympics in 2018. At 36, he'd likely be one of the oldest downhillers, but others have raced at that age and reached the podium.
Didier Cuche of Switzerland was still winning World Cup races at 37 before he retired. Bode Miller, who tied for third with Hudec in Sochi, was 36.
But if Guay is going to race at breakneck speeds for another four years, his knee has to be able to sustain it.
Two weeks after his arthroscopic procedure in March, he was still experiencing pain and swelling in his knee. Guay then made the decision to have the more invasive surgery.
"I needed to get (my) knee in a good place," he said. "Even if I start a little late, even if I miss the season entirely, I think I have to keep my eyes on the prize which is four years down the road.
"That being said, I'd like to start as soon as possible because I know how competitive my sport is. I know the more time you spend off snow, it's that much time you have to make up on the other competitors. I'm a little bit anxious to get back on snow and start racing again, but I need to give myself enough time to heal."
Guay won his first career World Cup medal in Lake Louise in 2003 when he was second in downhill. He's been a consistent top-10 finisher at the Canadian stop on the circuit.
He'll be in Lake Louise working with his sponsors, but won't race there for the first time in over a decade.
"It'll definitely be a strange feeling not to be in the start hut," Guay said.