Tadhg Furlong and Seán O’Brien both started for the Lions in Saturday’s win over the Crusaders, with Jack McGrath appearing from the bench.
With the Lions ahead 3-6, Sexton entered the game in the 29th minute as a replacement for Jonathan Davies. This saw Owen Farrell shift over to inside centre with Sexton slotting in at 10.
Farrell kicked a third penalty before the break to give the Lions a 3-9 lead at half-time.
The Lions pack was dominant for much of the game, particularly at scrum time, with Furlong looking impressive up against All Blacks Joe Moody and Wyatt Crockett.
The back line created nine line breaks but couldn’t find a finishing touch.
They didn’t need to. The Lions defence was resolute throughout, only allowing the Super Rugby leaders to score a single penalty in 80 minutes.
Farrell missed a kickable penalty early in the second half but made amends when he knocked over his fourth with 10 minutes remaining to all but guarantee a morale-boosting win.
The Lions next game is on Tuesday against the Highlanders in Dunedin (KO 8.35am Irish time).
Lions fixtures & results
13-7 win v NZ Provincial Barbarians, Toll Stadium, Whangarei (Saturday, 3rd June, KO 8.35am Irish/7.35pm New Zealand)
22-16 defeat v Auckland Blues, Eden Park, Auckland (Wednesday, 7th June, KO 8.35am/7.35pm)
12-3 win v Crusaders, AMI Stadium, Christchurch (Saturday, 10th June, KO 8.35am/7.35pm)
v Highlanders, Forsyth Barr Stadium, Dunedin (Tuesday, 13th June, KO 8.35am/7.35pm)
v Maori All Blacks, Rotorua International Stadium (Saturday, 17th June, KO 8.35am/7.35pm)
v Chiefs, FMG Stadium Waikato, Hamilton (Tuesday, 20th June, KO 8.35am/7.35pm)
v All Blacks, Eden Park, Auckland (Saturday, 24th June, KO 8.35am/7.35pm)
v Hurricanes, Westpac Stadium, Wellington (Tuesday, 27th June, KO 8.35am/7.35pm)
v All Blacks, Westpac Stadium, Wellington (Saturday, 1st July, KO 8.35am/7.35pm)
v All Blacks, Eden Park, Auckland (Saturday, 8th July, KO 8.35am/7.35pm)
