Following the lead of Neil Wagner, Southee pitched shorter, and came up with exceptional results after tea, claiming the wickets of key duo Dinesh Chandimal and Angelo Mathews – both caught out hooking.
Southee loves playing against Sri Lanka – his bowling average of 17.92 against them is his best against any nation, and his dismissal of Mathews was the seventh time he had claimed his wicket in test cricket - the most against any batsman.
The haul was also his best return at the Basin Reserve, and continues a fine run of test performances - his four wickets were key in beating Pakistan in the deciding test last week, and he took 12 wickets in two tests against England in March.
Southee, who turned 30 this week, said his short-ball strategy came about after an initial lack of success breaking the 133-run fourth-wicket partnership between Mathews and Dimuth Karunaratne.
"Early on it was nipping around and did swing a little bit, and then there was a bit of a dull period where they managed to get a good partnership when they needed it.
"At the time we needed something a little bit different, [the same approach] wasn't quite working, and it did kind of work today."
The "kind of" qualifier is a result of Niroshan Dickwella's belligerent unbeaten 73 from 91, which saw Sri Lanka through to 275-9 at stumps.
However, Southee believes that the Black Caps batsmen can take note of the runs on offer, and lays out a plan for his side to take control today.
"Our batsmen will take out of it that if you can get in, it can look reasonably easy.
"If we can turn up tomorrow and try and get that last wicket as quickly as possible, hopefully our batters can get stuck in."
