In the first heat Nicholls snuck past America's Charles Guldemond, who missed out on the fourth spot by just 0.75 of a point.
But it was Canada's Maxence Parrot who put in the best display of the day as he scorched the competition in the second heat of the men's snowboard slopestyle on Thursday to book his place in the Sochi Olympic final.
Parrot's score of 97.50 was the best of the day as the competition burst into life in the second heat. Roope Tonteri of Finland snared second with 95.75, which would also have been good enough to win the first heat.
The laconic Finn was impressed with the standard in the second heat, but told Reuters that it didn't affect him as he prepared for his second run.
"I don't really think about the level, I just want to stomp that run, I just want to do my own stuff, and it's turned out pretty well."
Sweden's Sven Thorgren led after the first run and held on for third place in the second heat, with Norwegian Gjermund Braaten in fourth as the two Scandinavians grabbed the final two automatic places for Saturday's final.
"The riding in this heat is just beyond," Braaten told Reuters as he waited to see if his run would be enough for a final place.
Braaten's final spot came at the expense of Belgium's Seppe Smits, who was just 0.25 of a point further back in fifth.
"I'm a little bummed. I was hoping that this run would be enough to make it straight to the finals but apparently everyone was ready to throw down, everyone went all-in. It was an insane level in the second heat," he told Reuters.
First heat winner Staale Sandbech's 94.50 would only have been good enough for third spot in the second heat as the competitors upped the ante in the bright Sochi sunshine.
Those who missed out on automatic qualifying still have the chance to grab one of four remaining berths when they compete in a semi-final on Saturday.
Earlier, Sandbech put in a blazing second run to win the opening heat on Thursday, the first day of competition at the Sochi Olympics.
Sandbech's first run scored a modest 45.25 but the Norwegian notched 94.50 on his second. Finland's Peetu Piroinen took second place, with Sebastien Toutant of Canada coming in third.
"I definitely had a good time this morning until I just got bumped out on that last run, which was very disappointing, but I've got to stay positive and move on to semi-day," Guldemond told Reuters.
"Obviously I wanted to make that top-four cut and it didn't work out, I just need to clean things up a little bit. But nothing ever came easy to me, but when it happened I thought, 'OK, I've seen this before!'"
Australian Scotty James recovered from a heavy fall to make his second run but failed to qualify automatically for the final.
Seen clutching his ribs as he left the slope after the first run, James revealed that his injury was actually in a much more tender place.
"I was really embarrassed, I actually hurt my 'man parts' real bad and I was in a lot of pain, and I didn't really know where to put my hands," he said.