Cummins had overseen wins in his first two matches since returning to skipper the team following his injury break and was still eyeing the treble after his Test teammate Travis Head had blasted a second half-century in succession to lead Hyderabad to 165 all out against the resurgent Kolkata Knight Riders.
But when Cummins' second over was smashed for 27 runs, with Finn Allen pummelling him for 22 of them, he reflected how it set the tone for visiting KKR to end up breezing to victory on 3-169 by seven wickets with 10 balls to spare.
"Not our best day. The margins are quite small and if I hadn't gone for about 30 in one over at the start, it might have been different as well," sighed Cummins.
"Those little moments can make a big difference."
The skipper was being a little harsh on himself, especially as after he'd sent a wide sailing to the boundary first ball and then got clubbed for 6, 2, 6, 4 and 4 by Allen, he did finally get his man on the seventh ball of the over, caught at deep midwicket.
After that, the skipper reverted to normal Cummins mode, and he went for only 20 off his other three overs.
But Sunrisers were never really in with a sniff as captain Ajinkya Rahane (43), Angkrish Raghuvanshi (59) and Rinku Singh (22 not out) guided KKR to their third-straight win.
Earlier, Head had bludgeoned 61 off 28, with nine fours and three sixes, but KKR's attack, including Cameron Green (1-34) who took the wicket of the dangerous Heinrich Klaasen and took two catches, had done well to blunt the Sunrisers.
The canny Sunil Narine (2-31) was once again their pick, becoming the first overseas bowler to take 200 IPL wickets with his double strike in a single over.
In the later match in Ahmedabad, it proved a painful night for allrounder Marcus Stoinis who, after hitting a brisk 40 in league-leading Punjab Kings' 9-163, was charged with bowling the death over with Gujarat Titans requiring 11 to win.
Keeping his nerve, he got the Titans down to needing three off his last two deliveries, but Stoinis served up a full toss off the penultimate ball which was whacked by Washington Sundar (40no) over fine leg for six.
