Shock loss to Rough Odds at Tauranga puts sprinter's Telegraph campaign in doubt.
Beaten trainer John Bell went to lengths to not blame rider Jason Waddell for Mosse's first defeat, at Tauranga yesterday.
Rival horseman Leo Molloy thought everything went to plan to bring undone the much admired Mosse with winner Rough Odds.
Bell, like almost everyone else, wanted to see Mosse make it six from six, but the tempo-related race did not go their way.
Mosse settled back last and could not sprint home fast enough to even get close to the pacemaking Rough Odds, who won by a margin.
"Leith [Innes] outrode us," said Bell simply.
"The winner ran home in 33 seconds from the 600m and there was no way we would have been able to get to the line in 32 seconds from last in running.
"It can't be done."
Molloy said his race plan had been based on exactly that.
"Over 1200m he'd been getting back and running on strongly and over 1400 I thought he'd be very competitive today.
"He had only to set a pace in which he could run home in 33 seconds and he was going to be difficult to catch."
So it proved. Mosse ran around the handful of rivals on the home bend and looked likely to score, but Rough Odds with the inside running raced away for a big win.
The disappointment for Bell is that the defeat may cause Mosse to miss the group one Telegraph at Trentham, a win being probably necessary to guarantee a position.
Mosse pulled a plate late on Tuesday and had to undergo a club veterinary examination yesterday to be allowed to run and he was inspected by the club's veterinarian after the race.
"He passed both beautifully," said Bell.
The small field was always going to turn into a tactical battle.
Bell said Mosse blew a fair bit after this race.
"Had he been running at 1200m yesterday it would have been perfect, but it wasn't for 1400m.
"At least it's got the [unbeaten] monkey off our backs."