Saints kicker Wil Lutz had the final say, nailing a 58-yarder with no time left for a dramatic 30-28 victory. Lutz missed a 56-yard field goal on the final play of the first half.
The teams combined for 13 points in the final 50 seconds — two field goals from Lutz with a Texans touchdown in between.
The Saints took a 27-21 lead with 50 seconds remaining on a Lutz 47-yard field goal. The Texans, though, needed only two plays to regain it.
Watson found DeAndre Hopkins for a 38-yard gain and then hit Kenny Stills for a 37-yard touchdown. Ka'imi Fairbairn missed the extra point, which would have left the game tied, but C.J. Gardner-Johnson drew a penalty for roughing the kicker.
Fairbairn made the second attempt, giving the Texans a 28-27 lead with 37 seconds left.
That was enough time for Brees, who threw completions of 15, 11 and 9 yards to get into field goal range.
Brees and Watson were outstanding. Brees completed 32 of 43 passes for 370 yards with two touchdowns and an interception, while Watson went 20-of-30 for 268 yards with three touchdowns and an interception.
Watson, though, will feel it tomorrow, taking six sacks and five other hits in the pocket. He was sacked an NFL-high 62 times last season, and despite the trade for left tackle Laremy Tunsil, now is on pace for 96 sacks.
He was injured on his 21-yard touchdown run in the second quarter but never missed a play.