If he does not play, the selectors will have to choose a third England captain of the summer for another crucial game. Hussain's choice of Graham Thorpe yesterday was, he said, instinctive. He thought it would be wrong to go back to Alec Stewart, overlooked Mark Ramprakash, and selected Thorpe because he was the next senior player, and, so he said, has a good cricket brain.
There was a plaster wrapped round two fingers of Hussain's right hand at the end of play, and although England are in a dire situation, he stubbornly refused to concede defeat. "They're in the box seats, but we're still in there fighting," he said, "though we've been playing catch-up since they bowled us out for 186."
Hussain looked on the bright side. Here was a chance, he said, for young players to show the country what they can do: 150s from Aftab Habib and Chris Read, a long innings from Dean Headley, and New Zealand would know they were in a fight. "There's no way I'm going to throw in the towel," he said. Of course not. But there's no way we need believe a word of it either.
His injury was definitely a defining moment: the 17th ball of the morning, when Hussain stuck the digital phalanx of the middle finger of his right hand - the top joint - in the way of an emphatic square cut by Adam Parore. He had gone the wrong way, he explained, and trapped his finger between the ball and his knee.
The ball slithered through Hussain's hands and dribbled towards third man, and the first evidence that this might be more than a routine misfield came from the behaviour of the two slips. When Parore took off for a run, neither Graham Thorpe nor Mark Butcher chased after the ball.
They must have heard a cry from Hussain because they continued to look towards him when Parore saw Andy Caddick trundling in and turned for a second run. Hussain said later that he knew he had broken the finger as soon as he took the hit, although he stayed on the field for another 18 minutes after the blow had been struck.
He went for an X-ray at the hospital of St John a couple of streets away, and the nurse told him it was a break as soon as she saw the negative. The last time Hussain broke his finger - it was the one next door - while playing for England against India in 1996, his recovery took three weeks.
He could not fit the fingers into a glove last night. He proposes to take painkillers and try again this morning, but he did not sound optimistic. He will ask the selectors to delay the choice of a substitute captain until the eve of the Third Test, but his medical history suggests he will not be fit.
Speculation had begun long before close of play: How many England captains will there be this summer? We have already had three: Stewart during the World Cup, Hussain, and now Thorpe. A fourth skipper seems inevitable: Ramprakash will be considered, but there is a veteran who could fill the gap - an in-form Lancashire batsman by the name of Atherton.
Thorpe seems an unlikely choice. He proved to be an undemonstrative captain yesterday. Only a churl would criticise his performance, but he might have brought on Phil Tufnell a little earlier and, if he really were captain, he would have had his work cut out reassuring Chris Read, the new wicket- keeper, who was having a torrid time.
Read's difficulties were not confined to keeping to Tufnell when the left-arm spinner did eventually come on at 12.17am. He seemed to be suffering from a crisis of confidence which would test the mastery of the finest of captains.