The England duo beat the Bains brothers of Kenya 15-5 15-8 and four hours later defeated Zimbabwe's Martin Murray and Jesse Engelbrecht 15-8 15-9.
"I didn't sleep very much last night so it was good to get back on court," said Nicol, who lost the singles to Canada's Jonathon Power.
"I think we have a great chance of the gold and we feel great playing together."
Fifth seeds Alex Gough and David Evans secured a quarter-final place with a 15-3 15-7 win over Papua New Guinea pair Derek Hunter and Damien Tam.
Scotland's Martin Heath and Neil Frankland beat Baitsi Motsamai and Kokolia Taoana of Lesotho 15-9 15-3.
England's Cassie Jackman and Tania Bailey beat Karen Anderson and Marlene West of Jamaica 15-4 15-7 to reach the quarter-finals.
Bailey is confident she and Jackman can make a big impact in their first tournament as a partnership.
"Cassie and I haven't played competitive doubles before but we have done lots of practice together," said the 22-year-old from Lincolnshire.
"We're hoping for a medal because it's anyone's tournament. None of the other girls have seen us play yet so that's an advantage."
Scott Fitzgerald and Katrina Hogan of Wales went out of the mixed doubles tournament after losing 15-11 15-6 to New Zealand's Leilani Rorani and Glen Wilson.
England's Chris Walker and Fiona Geaves beat Luke Fraser and Nicolette Fernandes of Guyana 15-8 15-8.
Gavin Jones and Karen Hargreaves of Wales beat Scotland's Martin Heath and Pamela Nimmo 15-12 17-15.
Scotland's other pairing also lost, Neil Frankland and Wendy Maitland going down 15-10 15-6 to Carol Owens and Daniel Sharplin of New Zealand.