But Norwich, who had been on the front foot for much the match, deservedly got back on level terms five minutes later when Jacob Murphy’s low drive caught out Town keeper Bartosz Bialkowski at his near post.
It was tough on the Polish keeper, who had been brilliant all afternoon, but it was the least the Canaries deserved from the match, although a point hardly helped their Sky Bet Championship play-off push.
The first opening of the derby arrived after only five minutes, with Jonny Howson seeing a close-range shot blocked after the visitors had failed to deal with a Murphy corner.
The second soon followed and it was again the Canaries who went close as Cameron Jerome hooked the ball just wide when well placed.
Ipswich thought they had claims for a penalty when David McGoldrick went down in the box as a corner came across but it was their neighbours who were looking the more likely to break the deadlock and would have done so in the 17th minute had it not been for a brilliant stop from Bialkowski.
It seemed for all the world like an own goal when Mitchell Dijks’ low cross clattered off Knudsen but the keeper produced a superb point-blank stop to keep the ball out.
The pressure from Norwich was pretty much relentless, although they struggled to create clear-cut openings.
Wes Hoolahan had a decent sight of goal just after the half-hour mark, but he fired wastefully high and wide, neatly summing up a frustrating first half for the home side.
Norwich thought they had opened the scoring three minutes into the second half but Dijk’s powerful close-range effort was rightly ruled out for handball.
The Canaries came straight at their opponents and it took another good save from Bialkowski low down to right to keep out Steven Naismith’s goal-bound header.
Ipswich weathered the storm, however, and took the lead against the run of play in the 62nd minute. The ball found its way to Jordan Spence out on the right and he picked out his fellow full-back at the far post, with Knudsen’s header giving John Ruddy no chance.
Bialkowski then made another good stop to keep out a powerful shot from Naismith but he was badly at fault for Norwich’s equaliser in the 69th minute.
He have had Murphy’s low shot covered but was beaten at his near post to hand the hosts a way back into the game.
The Ipswich keeper’s mixed afternoon continued six minutes later when he made another superlative one-handed save to palm Alex Tettey’s piledriver over the bar. He also stopped Alex Pritchard’s when it looked to be creeping in as Town held out for a draw.