Centre Gavin Henson scored two tries as the Lions claimed an error-strewn victory over Southland in Invercargill.
The Welshman put the Lions 10-0 ahead on seven minutes after Ronan O'Gara kicked an early penalty.
But after an encouraging start, the Lions made a host of mistakes against stubborn opponents who drew level with the help of a try from Hale T-Pole.
Henson added a second try on 54 minutes and three more penalties from O'Gara sealed an unconvincing triumph.
Although it was a disappointing performance from the Lions, it was a good response from Henson - whose inclusion in the game means that he is ruled out of the first Test against New Zealand this Saturday.
He deservedly claimed the man-of-the-match award but there were few others that would have made the Lions management team think again about leaving them out of the Test squad.
Even though the Lions started well, it was Southland that had the first chance to put points on the board but fly-half Richard Apanui fired his penalty wide after Matt Stevens was caught lying on the ball.
The Lions did get the points their bright start deserved with a penalty from O'Gara on seven minutes.
And they added to their lead soon after when Henson, who looked determined to prove a point throughout, produced a deft side-step to power over from close range.
Like the other team that the Lions have faced so far on tour, Southland showed their stubborn streak and Apanui reduced the deficit on 17 minutes after Moody was penalised for coming in at the side.
But the home side were helped somewhat by the tourists, who suddenly started to lose their incision and shape, despite some nice work from O'Gara and Henson.
The tourists had plenty of possession and territory but some sloppy back play, as well as failure to do the basics, meant that their domination was not converted into points.
Lions match skipper Michael Owen (L) tries to play in Ronan O'Gara
O'Gara did have the chance to put the Lions further ahead after Daniel Quate was penalised for a high tackle on Andy Titterrell but the kick from halfway went wide.
The miss did not spark the men in red however and their half was summed up when Simon Shaw was penalised for accidental offside when they drove menacingly to the Southland line.
And the home side could have made it even worse for the Lions only for Apanui to miss another kick at the end of the half.
Despite the undoubted half-time dressing down, the Lions conceded a try on 46 minutes when flanker Hale T-Pole barged his way over from a catch and drive near the Lions line.
Apanui added the extras to tie the score at 10-10 to spark fears that Southland could gain their first win over the Lions since 1966.
The Lions management team responded by sending on a host of replacements and on 54 minutes they regained the lead when Henson again showed his strength by powering his way over under the posts.
O'Gara added the conversion and a close-range penalty to put the Lions 10 points ahead but any thoughts that Southland would lie down were soon dispelled.
Southland piled forward and Henson, who escaped sanction for a couple of solid shoulder charges in the first half, was penalised for a third such tackle on 64 minutes and Apanui kicked the points.
Roared on by a vocal Invercargill support, Southland continued to ask questions and despite another O'Gara penalty, Apanui's kick on 76 minutes kept the home side to within seven points.
The win was sealed however when O'Gara slotted a simple close-range kick late on and although the Lions have another win under their belt, there is plenty for head coach Sir Clive Woodward to think about.
Southland: Wilson; Harrison, Milne, Muliaina, Lotawa; Apanui, Cowan; Miller, T-Pole, Tamariki; Quate, Macdonald; Dempsey, Rutledge, Dermody (capt).
Replacements: Murch, Hall, Logan, Wright, Clarke, Petre, Te Whare.
British & Irish Lions: Murphy; Cueto, Smith, Henson, Hickie; O'Gara, Cooper; Stevens, Titterrell, Hayes; Shaw, O'Callaghan; Moody, Williams, Owen (capt).
Replacements: Bulloch, Sheridan, Easterby, Cusiter, Hodgson, Shanklin, D'Arcy