Atlanta United and Los Angeles FC both missed a chance to strengthen claims of winning their respective MLS conferences after they played out draws against the Seattle Sounders and Portland Timbers.
Eastern Conferences leaders Atlanta were held to a 1-1 draw by 10-man visitors Seattle on Sunday.
SIGN UP to watch MLS games LIVE and on-demand on DAZN
Atlanta were ahead of New York City FC on goal difference prior to kickoff having played the same number of games, but fell behind to Nicolas Lodeiro's penalty on the stroke of halftime.
Leading scorer Josef Martinez responded for the hosts early in the second half, when he looped a header over Sounders goalkeeper Stefan Frei for his 19th goal of the season in front of a record MLS crowd of 74,243 at Mercedes-Benz Stadium.
The Sounders were reduced to 10 men when Jordan McCrary received a second yellow, but they defended gallantly in the final half-hour, despite Leandro Gonzalez-Pirez hitting the bar from close-range.
The Five Stripes now sit one point in front of second-place NYCFC, and six points ahead of the third-place New York Red Bulls.
19 and counting for @JosefMartinez17... pic.twitter.com/QtJs3pVQQM
— Major League Soccer (@MLS) July 15, 2018
Elsewhere, LAFC missed an opportunity to close the gap on Western Conference leaders FC Dallas to one point after a goalless draw against Portland.
Chances were at a premium for both sides on a humid evening in California, but the game came to life with five minutes remaining when Lee Nguyen received a straight red card for a challenge on Sebastian Blanco.
Despite being a player down, LAFC could have won it in stoppage time as Mexico international Carlos Vela headed straight at Jeff Attinella from six yards.
ALMOST on the header from Carlos Vela! #LAFCvPOR https://t.co/J0u66gLfJx
— Major League Soccer (@MLS) July 16, 2018
Portland climb up to fourth in the Western Conference and have games in hand on the teams above them, while Seattle's point edges them away from the bottom of the table.