The Wales flanker led the Lions for the first time in the win over the Queensland Reds but with fellow Welshman Justin Tipuric as well as Sean O'Brien both impressing in the red No. 7 shirt, Warburton has had it far from his own way in the race for a Test spot.
And despite producing an impressive individual performance in the convincing 47-17 win over the New South Wales Waratahs, the Cardiff Blues man is not taking selection for Saturday's first Test as a given.
"The part of captaincy I don't like is if you become complacent and you think you have a starting place in the team," said Warburton.
"I like it when you go into the team announcements and you're on edge because you don't know whether you're going to get picked or not.
"Knowing you might not be involved is what keeps you going in training and keeps you dedicated off the pitch as well."
Warburton formed part of a high quality Lions back-row last weekend, Tom Croft and Jamie Heaslip the others to start alongside him in Sydney.
But with Warburton's international team mates Tipuric and Toby Faletau beginning tomorrow's match with the Brumbies, there may still be time for some players to make a late claim for a starting spot.
Head coach Warren Gatland has insisted Test selection is yet to be confirmed and his coaching team will only discuss the squad for the opening game with the Wallabies after tomorrow's match.
"Warren has emphasised in meetings that he feels he has a squad where everyone can compete for a starting place and that's the best way to be," said Warburton.
"Everyone's on the edge in training, you can tell everyone is lifting their level from international level. All of the players are gunning for that spot."
Unbeaten so far, the Lions have recorded some convincing victories, the win over the Waratahs perhaps their most impressive performance to date.
But despite easily disposing of the likes of the Reds and the Western Force, Warburton insists the three match Test series will be closely fought.
"Every time a Lions tour comes around, the national side we're playing against, whether it's South Africa like last time or New Zealand before that, they always seem to come good," he said.
"That shows how much it means to them to be involved in a Test series. None of us will be expecting an easy ride at all."