Iain Henderson has offered a stiff defence of the Lions' disappointing opening tour match by insisting he would have been more surprised if the tourists had fired on all cylinders.

Warren Gatland's side took on a New Zealand Provincial Barbarians side in Whangarei just days after their arrival in the country, and the hosts made a real game of it before succumbing 13-7 at Toll Stadium.

There were few standout players in the Lions' display, but Henderson put the lacklustre outing down to the acclimation process.

"A few of the boys are a bit tired and a few have been a bit sluggish in training these last few days, but that was to be expected," the Ulster forward, who made his Lions debut before being replaced early in the second half, told RTÉ Sport.

"If everything was to go perfectly today, if everything was to look phenomenal and work like clockwork, that would have been more surprising than the performance we had this evening. 

"There were some positives in the game. We were stringing a good few nice pieces of play together and we got over their goal line three or four times but were held up. 

"We need to be more clinical, then maybe we'll get some more points on the board."

While the Lions were making their debut as a unit, their opponents were also an unfamiliar outfit, a selection of the top players from outside the Super Rugby franchises coming together to take their shot at the men in red.

And Henderson was quick to pay tribute to the Barbarians side, who led 7-3 at half-time and also threatened to snatch a late victory.

"Those boys came out a highly motivated team," he said. "They came and threw it all at us.

"They'd a few big boys, a few good players, they wanted to come out and play a bit of ball and have bit of fun, and don't get me wrong, they did. The first half, they were definitely ready.

"For ourselves, similar to them, we haven't fully had time to gel as a defensive or attacking unit, however, we'll have time tomorrow morning to review our game and we'll look at what we can build on and what we can better at for the next two games."