Upshaw remained hospitalized in critical condition Sunday evening at Spectrum Health after he collapsed on the court in the closing seconds of Saturday's regular-season finale.
Drive President Steve Jbara said the team "is doing as good as you can expect given the circumstances.
"They're devastated about their teammate, but they're sticking together and working through it," he said Sunday.
Most of the players spent the day together, he said, and "at this point, the guys are still planning to play" Wednesday.
"It's obviously been a roller coaster day, but we're all staying positive," said Jbara, who has received updates on Upshaw's condition. "At the end of the day, Zeke's situation is on our minds and basketball is second."
In that last game, the Drive won, 101-99, over Long Island to clinch their first playoff berth in four seasons as the G League affiliate of the Detroit Pistons.
Upshaw was pursuing a defender headed into the left corner when he collapsed and landed on his stomach.
"I immediately knew it was terrible because he wasn't moving," said Drive public address announcer Eric Zane. "What was remarkable was how fast a lady came out - within 10 seconds - she came sprinting out there with a defibrillator."
Zane did not know if the defibrillator was used.
The Drive finished as the No. 2 seed in the Eastern Conference. At 29-21, they enter the four-round, 12-team playoff format on a six-game winning streak. The first three rounds are single-elimination with a best-of-three finale.
Other first-round Eastern Conference playoff games Wednesday have Lakeland at Erie and, in the Western Conference, Texas at Rio Grande and South Bay at Oklahoma.
Additional games are expected to be announced soon by the league.