Gibson left the game Friday in the first quarter after rolling his left ankle. He was able to limp off the court on his own, but did not return. Gibson is expected to be day-to-day (source)
With Gibson out, Nikola Mirotic should see an increase in minutes against bigger lineups, and Tony Snell, who has been getting big minutes, should also increase in the rotation. Mirotic was able to put up good numbers at the beginning of the season when he was given a good run of play. Mirotic is worth watching in standard leagues to see how the Bulls play him, and a pickup in deeper leagues.