Diggs missed the last two games with a groin injury but was a full participant in practice Thursday and Friday. He also was listed with an ankle injury. He has 23 catches for 395 yards and four touchdowns in five games this season.
"He's a playmaker," Keenum told the Pioneer Press of Diggs. "He's a huge playmaker ... it's big for the offense."
The Vikings also listed as questionable wide receiver Michael Floyd (hamstring), tackle Riley Reiff (knee), guard Nick Easton (calf) and cornerback Mackensie Alexander (hip). Reiff and Alexander were full participants in practice while Floyd and Easton were limited.
Bradford will sit out for the sixth time in seven games. He last played in Week 5 against the Chicago Bears on Oct. 9.
Bradford reportedly made the trip to London but has not practiced in three weeks. According to ESPN's Chris Mortensen, Bradford got five injections in his injured left knee last week as part of treatments he received to help relieve the inflammation.