A 22nd-minute goal from Nemanja Nikolic – after a smart Dax McCarty pass – led the Fire to a 1-0 win at home against Columbus on Saturday.
Columbus remains top despite seeing a three-match winning run ended.
Portland is clear atop the Western Conference and recorded a come-from-behind 3-1 win against the Philadelphia Union.
Richie Marquez had put the struggling Union – who are bottom in the east – ahead, but Darlington Nagbe levelled before the break for Portland.
A Roy Miller goal and a Fanendo Adi penalty secured the points for the Timbers, who are three points clear at the top.
Adi's strike was his 46th for the club and saw him become the Timbers' all-time leading scorer.
New York City's inconsistent start to the campaign continued as the side was beaten 2-1 by DC United despite a David Villa goal.
Sebastian Giovinco was on the score sheet for Toronto, which drew 2-2 with high-flying Atlanta United.