The situation was far better a little earlier, with 45 runs to defend in four overs. But Kieswetter carted Abu Nechim's 17th over for 16 runs to drastically reduce the cushion. Lasith Malinga came on for the 18th over with wickets in his sights, but Somerset worked him around for seven runs, and crucially denied him a strike. With set batsmen at the crease, Somerset needed 22 to win off 12 balls, and Harbhajan found himself in a catch-22 situation.
Ball in hand, Harbhajan trotted from his position in the covers to Ambati Rayudu, who was having a terrible day behind the stumps. Surely the captain was going to confront the pressure head-on and bowl the 19th over himself? Kieron Pollard moved over from his fielding position and joined in the discussion. Hands were waved, gestures were made, and at long last, a decision was taken. As far as radical choices go, this one was from well beyond left-field - James Franklin was brought on for his gentle trundlers on a length.
Harbhajan was skating on thin ice, on several counts. Irrespective of the outcome, his decision to abstain from bowling was going to be questioned. He had come under criticism in England for shying away from his responsibility as a senior bowler, but here he also had the responsibility of having to lead from the front.
Additionally, the 19th over had been bowling sides' banana peel right through the tournament, with even Dale Steyn failing twice in the over of the devil. Alfonso Thomas, the Somerset captain, had won his side a game with a brilliant 19th over, but had stumbled at the same hurdle earlier in the day. With a T20 economy-rate of 8.12, and just four overs in the tournament prior to this game, Franklin was virtually set up to fail.
Harbhajan was backing his gut feel with solid plans, though. His best fielders - Pollard and Aiden Blizzard - were dispatched to the positions where slogged length balls were most likely to go: deep midwicket and long-on. There was also protection at deep backward square leg and square on the off side, so Harbhajan had most bases covered. Over to Franklin.
The first ball was on a length, and Jos Buttler muscled it between Pollard and Blizzard, who tag-teamed on the edge of the field to deny the boundary. The next ball should have also gone for four, but Buttler smashed a low full toss straight into Kieswetter's forearm, leaving him writhing in pain and bringing about a lengthy stoppage in play. As it transpired, the break killed Somerset's momentum, and ultimately their campaign. Buttler lost his stumps after missing a frustrated slog off the third ball, and Kieswetter holed out off the next ball he faced. Malinga then easily closed out the game in the 20th by detonating the stumps twice.
"I always wanted to ensure we had the luxury of several options in the end," Harbhajan explained later. "I definitely wanted to keep Malinga for the last over because, if it came down to eight or tens runs to defend in six balls, he is the only guy who can actually defend those runs. Franklin and Pollard were all ready for any kind of situation; I kept them alert from the 15th over onwards, I had told them it could be me, Pollard, Franklin or [Yuzvendra] Chahal.
"Given the situation - 22 runs in 2 overs with the wicket keeping low - I decided to go with Franklin and he responded really well."
Despite Harbhajan's lucid line of thinking, Mumbai had fortune favouring them once again, as it had done right through the tournament. If Buttler's power-drive off the second ball had gone a foot either side of Kieswetter, it would have come down to 16 off 10 balls and Franklin would have felt the pressure. As it transpired, the shot homed in on Kieswetter like a guided missile, leaving him maimed in addition to robbing Somerset of a crucial boundary.
The luck was with Mumbai once again, as it had been when MS Dhoni fluffed a simple stumping to reprieve Lasith Malinga, when Daren Ganga pushed his field back inexplicably with two to defend off the last ball, and when Denesh Ramdin missed a straight-forward run-out from two yards away.
In summation, Harbhajan had been mighty brave ahead of the 19th over, and fortune chose to honour its half of the deal. It has taken Mumbai Indians to within a step of their first tournament win, but their opponents on Sunday will match them in both, daring and hunger. Here's hoping for a humdinger.
Nitin Sundar is a sub-editor at ESPNcricinfo