It's hard enough beating Oracle Team USA - but the clock as well?
It was like watching Ferraris race on flat tyres. The wind - which seemed to be building dangerously towards OTUSA's comfort zone - suddenly dropped away to a measly 9 knots on a foggy San Francisco Bay.
They still managed 20 knots at times but both boats, especially OTUSA's, looked de-powered. On leg 4, Team NZ were a kilometer ahead.
But they faced a new enemy. Not too much wind, not enough wind. The time limit to complete the race is 40 minutes - but it was obvious on the upwind leg that Team NZ were going to fall foul of the clock.
Consider the cruel injustice of this. They win by a street but the America's Cup rules also include a maximum time limit as well as wind limits - and they couldn't make it in time.
Twice before ETNZ have suffered the teeth-grinding indignity of being in front with the Cup at their mercy, only for the race to be called off when the wind limit was exceeded.
There was no danger of that yesterday. The usual blistering start and sprint to the reaching mark was like watching two old men walk their dogs to the street corner.
OTUSA skipper Jimmy Spithill got the better of it and blocked the Kiwis well off the mark to starboard. They turned 10s ahead - the margin exaggerated by the lack of wind - but ETNZ, with eagle-eyed Ray Davies doing a fine job in picking up wind shifts , got well ahead on the downwind leg.
They swiftly got to a 500m lead but, on the upwind beat, it became obvious that their vast superiority on the course was not going to beat the inexorable certainty of time.
Spithill can be glad he luffed the Kiwis out to starboard in this race, as it saved his bacon, slowing matters down until New Zealand were not even at the final mark when the 40m limit came up.
It was a bitter irony. Will the wind ever suit New Zealand?
We will know in about an hour. The wind still seems light. There will be another race today but it may not be terribly different from the first.
San Francisco's wind, which usually builds during the afternoon, seems to have taken a day off.
The next race is scheduled to begin at 9.32 NZ time.
Check out all the pics from the slowest race so far: