On the first game of their 10-match tour, Warren Gatland’s side were slow starters as they were pushed all the way by the home team at Toll Stadium in Whangarei.
Anthony Watson’s second-half try eventually proved decisive as the Lions started with a win, but Faletau was the standout performer for the men in red.
The Barbarians side, which included Gatland’s son Bryn at fly-half, were a scratch team put together especially for this game, but they looked by far the more complete of the two outfits.
With Bryn Gatland driving his team, the Barbarians fell behind to an early Johnny Sexton penalty after a Ben Te’o carry had given the Lions field position.
Centre Te’o was prominent early on, but the Barbarians were surprisingly able to keep the Lions at bay for most of the first period.
A Sam Anderson-Heather try – which was a deserved reward for their efforts – and a Gatland conversion put them back ahead 7-3.
That ended up as the half-time score as the Lions, whenever they scented a try, threw away the chance of scoring. Stuart Hogg passed up one great opportunity, his poor pass seeing Watson forced into touch.
Faletau had earlier saved what looked like being a Barbarians try with an incredible try-saving tackle with the Lions needing a response at the start of the second half.
Both Faletau and Moriarty had carried hard for the Lions, and their team began with a bang on the game’s resumption. Scrum-half Greig Laidlaw, taking over kicking duties with Sexton nursing a knock, slotted a penalty to narrow the deficit to just a single point.
The three points came after the Lions had turned down two kickable penalties in the first 40.
Owen Farrell, George Kruis and Jamie George were then introduced on the 50-minute mark, and the Saracens trio made an almost immediate impact.
Yet another surge from the powerful Moriarty gave the Lions momentum and Farrell’s short pass found Watson who finished impressively by crashing through two home tacklers.
Farrell converted and that proved to be enough to narrowly hold off the plucky Barbarians, but the Lions will know they’ll have to improve and quickly before Wednesday’s clash with Auckland Blues.