Toronto topped Milwaukee 118-112 in double overtime, cutting the Bucks' series lead to 2-1 in the important first leg of its home stand.
"The beginning (of the game) set us in a really bad spot," Gasol said. "We couldn't get a grip of the game early on."
Oklahoma City Thunder star Russell Westbrook posted 21 points, 11 assists and 12 rebounds on Saturday.
Marc Gasol's move from the Memphis Grizzlies to the Toronto Raptors was confirmed.
This week was one full of transactions across the board in seemingly every major sport in the US.
The Grizzlies were shopping both Mike Conley and Marc Gasol before Thursday's trade deadline, but opted to keep the former.
The Grizzlies have been open to trading Marc Gasol for a few weeks now.
The Wizards lost guard John Wall for this season and potentially next season this week with a ruptured Achilles tendon.
Conley entered play Tuesday averaging 20.3 points and 6.3 assists per game in 2018-19.
Gasol will sit out Tuesday's game against the Timberwolves, as Memphis and Charlotte are reportedly structuring the framework of a deal.