Sam Warburton blamed indiscipline for the British and Irish Lions' 23-22 defeat by the Highlanders in Dunedin.
The Lions slumped to the second loss of their four matches to date despite leading 22-13 in the 54th minute, paying the price for conceding 12 penalties to the hosts' five.
"There was a string of four penalties in that second half when we were in decent territory, but we gave away four penalties in a row," Lions captain Warburton told Sky Sports 1.
"That gave them way too much territory and momentum and they scored off that eventually.
"Our discipline on Saturday (against the Crusaders)....we kept penalties to single figures and for one reason or another that didn't happen here.
"You have to give the Highlanders credit because they forced the pressure to give away penalties, but we have to keep penalties to single figures."
The failure to capitalise on their try-scoring opportunities has been the Lions' greatest shortcoming so far on tour, but Warburton, Tommy Seymour and Jonathan Joseph crossed against the Highlanders.
"We gave away too much possession at the breakdown, our first and second arrivals weren't there quick enough and that's something we spoke about during the game," Warburton said.
"They were pretty hard on the ball, so give them credit there, but we turned over too much ball on attack.
"We scored more tries than we have done and when we were direct we looked pretty good. It was a proper game of chess and was tight.
"We need to come away from these with wins and I'm sure there were a few key moments in the game that if we could go back in time, we'd change them."
Lions head coach Warren Gatland echoed Warburton's view that the penalty count was decisive, but also rounded on his players' game management.
"We didn't nail a few big moments that were important that would have put ourselves reasonably comfortable when we were 22-13 ahead and we let them back into it which is disappointing," Gatland said.
"The penalty count was reasonably heavy against us as well and that's a concern. To be in front but lose is disappointing. There were a couple of chances we didn't take.
"We knew how tough it would be coming to New Zealand and we need to make sure we learn from these experiences.
"Going into the Test matches we'll be really battle hardened because the players are learning about playing for 80 minutes and being clinical."