With the British and Irish Lions squad announcement on Thursday, Wednesday Night Rugby spoke to Matt Williams and BBC Sport's rugby correspondent Chris Jones.
Williams believes that the number ten position is particularly tricky for Lions coach Warren Gatland.
Lions tour
"If he is covering his bets, that will mean Sexton goes. But with a huge question mark on him," Williams said.
"[Gatland] has to be sure that Owen Farrell is going to make that Test side at 10 - and I'm not so sure he will. Will he put Farrell at 12? He could, but Henshaw has been the best 12 in the northern hemisphere, so he is in this dilemma.
"That dilemma might come to Sexton's rescue because Finn Russell proved you can't trust him with a Test match. You can't trust him with making the best decisions in a Test match. Finn did himself huge damage in the Six Nations; the drop goals in the last minute, tripping players - Gatland will just look at him and say 'I don't trust him.'
"He'll go because there is politics and a certain number have to go. But he'll play in the seconds, and Dan Biggar will go - Dan Biggar will start in the Test matches."
Sexton
Williams believes that Sexton will be lucky to make it on tour.
"I think it's a big, big gamble to take Johnny on tour. There is no doubt he'd be wonderful; he's a leader, he had been on so many trips, his wisdom, his knowledge - and his attitude, the man is ruthless. That is what you need.
"When Brian O'Driscoll went on the 2001 trip, he was a young man - all of a sudden he came into contact with Martin Johnson, Dallaglio and these guys. He came back a different man. They didn't care that he scored three tries against France and he was a lovely bloke; they wanted a ruthless mongrel on the field.
"Sexton is the perfect tourist, but you can't take Sexton if he lasts 20 minutes in a match. It's a very short tour. He is swinging in the balance."
'Imponderables'
Jones had his say on the back row positions.
"I know that Owen Farrell splits opinion, especially outside England, but I would be staggered if Gatland is not going to pick Farrell given what he did for him in 2017. That means that one of Sexton or Russell is missing out.
"I'm just fascinated as to that selection meeting - to what extent Townsend is pushing for Russell, to what extent Gatland will feel that he can go without Russell, who offers something different.
"Do they want Russell off the bench or is that pie in the sky? Maybe they want a strategic game manager in the mould of Dan Biggar and play Sexton or Farrell at 10. Does Farrell play 12 with Biggar or Sexton at 10?
"There are so many imponderables, but it is just mad that Sexton is either the starting 10 or not in the 36."
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