Grujic watched on from the stands as Liverpool drew 3-3 with Arsenal in the Premier League.
Forster returned from a 10-month lay-off in a 2-0 win over Watford.
Celtic have been linked with a number of players this month.
The youngster is set to stay at St Andrew's until 2019.
The 17-year-old will not feature for Leeds United against Manchester City in the academy competition.
Jack Hunt left Crystal Palace to sign permanently for Sheffield Wednesday.
The Tunisian has not played a single game for the club.
Christian Eriksen has scored just four goals for Tottenham Hotspur so far this season.
Liverpool drew 3-3 with Arsenal at Anfield last night.
West Bromwich Albion drew 2-2 with Chelsea last night.