DOUBT surrounds Brisbane Lion Mitch Golby's inclusion against Carlton on Saturday night with the in-form half-back unsighted at training on Friday.

Sam Docherty, despite not being named in the Lions' original 22, looms as a likely replacement with vice-captain Tom Rockliff seeming to let the cat out of the bag.

"We're pretty confident in the two blokes coming in. First gamer in Sam Michael, gets his chance which is pretty exciting and Sam Docherty, he'll add a bit of run off the backline for us," Rockliff said on Friday.
  
Michael and Josh Green were the two new names originally named to replace Merrett and Clarke.

Docherty was taken with the 12th pick of the 2011 NAB AFL National Draft and after injuries interrupted his first season, the running defender has played twice this year.

He debuted with 20 disposals against North Melbourne in round four and was a substitute the following week before being left out.

Rockliff said it was exciting to see the 199cm Michael make his debut.

Michael was upgraded from the rookie list on Thursday to cover the long-term injury loss of midfielder Claye Beams (ACL).

Michael can play key position at either end of the ground as well as ruck, and is one of the best endurance runners at the club.

Rockliff said he expected a much different performance from Carlton compared to the the Lions' defeat of them in March's NAB Cup Grand Final.

"I think they were still learning the new game style and I think over the last couple of weeks you've seen they've started to pick that game plan up," he said.

"The shift of (Andrew) Walker off half-back has been good for them and we have to look to nullify him. Also their keys, they've got (Jarrad) Waite back who can be a match-winner so we've got to look to nullify him as well.

"I think we'll go about it the same way. We'll look to shut their ball movement down and look to counter attack and give our forwards a chance to kick goals."

Michael Whiting covers Brisbane Lions news for AFL.com.au. Follow him on Twitter: @AFL_mikewhiting