The under-pressure Portuguese coach faces two crucial Premier League games in the coming weeks and an FA Cup fourth-round replay, as well as trying to overturn a 3-1 Champions League last-16 deficit against Napoli.
"They are key just because we can be out of or continue in two competitions," he said ahead of Saturday's league game at West Bromwich Albion.
Asked if March was a defining month, he added: "It can define a 'trophyless' season for Chelsea, yes."
Adding spice to life at Chelsea this week were reports that Real Madrid coach Mourinho was spotted in London house-hunting.
But Villas-Boas insisted he was unconcerned about rumours linking his mentor with a return to the London club.
"The only place where Jose's shadow isn't lurking is Barcelona. It's everywhere else in the world," said Villas-Boas.
"If you can train a manager to be the best in the world, everyone wants him."
He added: "There is a doubt over the future that lies in every single job in our lives, in mine and in yours.
"Everybody is more or less under threat with positive or negative results."
Source: AFP
Source: AFP