The All Blacks forwards won the battle of the breakdown in their 30-15 first Test victory at Eden Park last weekend and a disappointing showing from Welshman Alun Wyn Jones means an overhaul of the Lions second row is likely.
England’s Maro Itoje is expected to start after adding more energy when he came on off the bench and strong displays from Courtney Lawes and Iain Henderson against the Hurricanes on Tuesday added more alternatives to the mix.
The locking pair impressed Gatland both in contact as well as with the ball in hand in the 31-31 draw with the Super Rugby champions, the final midweek match of the tour.
And Gatland says: “I thought Courtney Lawes carried well in the first half. Lock is a position right from the start that we knew we had a lot of strength in.
“Those two guys had really strong games... to give us some food for thought.
“It will be a toss-up in terms of selection.”
Henderson possibly blotted his copybook when he was yellow-carded for a dangerous tackle on Jordie Barrett, which allowed the Hurricanes to storm back from 31-17 down.
That ill discipline could count against the Ulsterman and Lawes coming off in the 54th minute could be a sign that Gatland had seen enough to include him in his second Test squad.