New Zealand were 77 for 1 and trailed England by 134 runs at stumps on day three with Williamson (16) and Fulton (41) unbeaten at the crease.
Wellington: New Zealand reached 77 for 1 at stumps on the third day of the second Test against England, still 134 runs behind the tourists after being forced to follow on. England bowled out New Zealand for 254 early on Saturday in reply to their own first innings of 465, with Stuart Broad taking 6-51 and Monty Panesar claiming the wicket of opener Hamish Rutherford before stumps.
Peter Fulton and Kane Williamson provided some resistance later in the day, adding 52 runs before stumps. Fulton was 41 not out. "Obviously we're disappointed with the way we batted in the first innings but Peter Fulton and Kane Williamson have done a good job to pull us back a little bit," New Zealand's BJ Watling said.
"If we can bat well on Sunday morning and cut that deficit, hopefully we can put a few runs on and have a target to bowl to." The New Zealanders may also be hoping for rain over the last two days of the Test to stall England's momentum. Showers are in the forecast for Sunday and Monday.
Broad laid open the New Zealand middle order in the first innings by dismissing first Test century-maker Rutherford (23) and Ross Taylor 0 before stumps on Friday, leaving the hosts 66 for 3 overnight. He took four more wickets on Saturday to approach his Test-best figures of 7-72 to help end New Zealand's first innings 12 runs short of its follow on target of 266.
Brendon McCullum (69) and Watling (60) produced the only threat to England's dominant position Saturday when they shared a partnership of exactly 100 for the sixth wicket.
But when an out of sorts Steven Finn dismissed McCullum to end the partnership nine overs after lunch, Broad was able to dislodge Watling and then run through the lower order and complete his seventh Test bag of five wickets or more.
Broad first took a catch to dismiss Tim Southee (3) off Finn, then edged out No. 10 Neil Wagner (0) and No. 11 Trent Boult (2) to end the New Zealand innings a few minutes after scheduled tea. Watling said he and McCullum had done their best to break England's stranglehold on the match.
"I tried to grind them down a little bit and Brendon played his natural game," he said. "It worked for us. We got a good little partnership going and it would have been nice to keep going.
"I think we lost a couple of wickets early this morning so I think it was about rebuilding and trying to grind them down. It was disappointing to get out five overs into the new ball." England captain Alastair Cook deliberated carefully over the decision to enforce the follow on.
Cook had to weigh the already heavy workload of his bowlers. James Anderson and Finn had bowled 25 and 20 overs respectively during New Zealand's first innings and Broad had bowled 17.2 overs.
But with only a session remaining on the third day, and with Panesar to take some of the strain when the ball grew older, Cook decided to enforce the follow on, hoping to take a lead in the three-match series after a drawn first Test.
England's stocks rose when Rutherford, who made 171 in his debut innings in the first Test, was dismissed for 15, caught by Ian Bell off Panesar when New Zealand was on 25.
Fulton and Williamson guided New Zealand to stumps without further loss but still needing 134 runs to force England to bat again.