Cockburn, a Wooden Award candidate who sustained a concussion in a double-overtime loss at Purdue last week, missed his second consecutive game for Brad Underwood's squad due to concussion protocols.
Curbelo, who returned last week after being sidelined for nearly two months with a concussion, is out due to COVID-19 health and safety protocols.
Illinois had lost back-to-back games but was able to cool off a Michigan State team that was 10-1 in its last 11 games entering Tuesday.
Per school officials, the timetable for both Cockburn and Curbelo to return is unknown.
Illinois has weathered challenges all season. Only four players on the roster have participated in all 18 games.
Tuesday was Curbelo's 13th missed game this season. Prior to this stretch, Cockburn had missed the team's first three games due to an NCAA suspension for selling team gear.
Illinois is a completely different group without Cockburn. It's recorded 118 points per 100 possessions, a 59.8% effective field goal percentage and a 42.1% clip from the 3-point line with Cockburn on the court, per hooplens.com. Without him? Those numbers significantly change: 101 points per 100 possessions, 47.9 effective field goal percentage and a 32.7% mark from beyond the arc.
Prior to the game, Underwood said he's focused on the positives with his team, despite its challenges. The adversity his team has faced this season, he said, will continue to help it grow.