Connaughton missed the final two preseason games with a sore right calf that the team initially hoped wasn't serious, before an MRI on Friday revealed the injury. Bucks coach Mike Budenholzer said earlier in the week that the team was not sure how Connaughton suffered the injury.
"We don't think it was an incident in a game," Budenholzer said before Wednesday's game against the Brooklyn Nets. "There's something that's just not quite 100%, not perfect, so this time of year we can be extra cautious."
Connaughton's injury leaves the Bucks without one of their key reserves to start the season through at least early November. He put up career highs in minutes (26.0), points (9.9), rebounds (4.2) and 3-point shooting percentage (39.5%) in 65 games (19 starts) last season, which led to a three-year, $28.5 million extension during the offseason.