Livewire All Black wing Rene Ranger will have to wait and see whether he starts Saturday's Super Rugby semifinal clash with the Reds after being bracketed with Lachie Munro.

The Blues will monitor how Ranger, who has been missing since Round 17 with a hamstring strain, gets through a full training, whilst also keeping an eye on Munro who has been nursing some sore ribs this week.

Either way it is a major call for Blues head coach Pat Lam, who will be forced to weigh up the game-breaking qualities of Ranger with the outstanding goal kicking attributes of Munro for the knockout match.

Lam admitted he had a gut feeling as to who would start, but would hold off on making the crucial decision until closer to kick-off.

"It's a tough decision as we go through it but it's about getting through training, getting over to Brisbane and then making a call when we get over there [in Brisbane],” he said.

"We've still got plenty of time, we've got three days before the game and it's seeing how they both come out of training.”

The only other change to the starting XV for Saturday's match at Suncorp Stadium comes at lock, with Anthony Boric's injury paving the way for loose forward Chris Lowrey to assume the locking duties.

Lam said while Boric, who has been at the heart of the Blues line-out this year, would be a huge loss to the team, he had plenty of faith that Lowrey would step up to the mark.

"He's a massive loss,” Lam conceded.

"The experience, the form, just the fact that he is a lock is a big loss for us but hey we've had that all season. With all the players that we have lost we just have to move forward and I'm really confident that Chris Lowrey will do a good job as well as Ali and the other forwards.”

The only other lock in the Blues squad is wider training group player James King who is still overcoming a knee injury and has been bracketed on the bench with loose forward Mat Luamanu.

Blues: 15 Jared Payne, 14 Joe Rokocoko, 13 Benson Stanley, 12 Luke McAlister, 11 Lachie Munro/Rene Ranger, 10 Stephen Brett, 9 Alby Mathewson, 8 Peter Saili, 7 Luke Braid, 6 Jerome Kaino, 5 Ali Williams , 4 Chris Lowrey, 3 John Afoa, 2 Keven Mealamu (captain), 1 Charlie Faumuina.
Replacements: 16 Tom McCartney, 17 Tevita Mailau , 18 James King/Mat Luamanu, 19 Daniel Braid, 20 Chris Smylie, 21 Lachie Munro/Rene Ranger, 22 Winston Stanley/Sherwin Stowers.

Date: Saturday, July 2
Venue: Suncorp Stadium, Brisbane
Kick-off: 19.40 (09.40 GMT)
Referee: Jonathan Kaplan (South Africa)
Assistant referees: Stuart Dickinson (Australia), James Leckie (Australia)
TMO: George Ayoub (Australia)