Valeri had a mostly open net in the 84th, but Sean Johnson scrambled to cover and blocked it over the post.
The Timbers (12-9-8) took first place in the Western Conference, moving two points ahead of the Seattle Sounders. Portland’s Mattocks and Vytautas Andriuskevicius left in the second half because of injuries.
NYC dropped to 15-8-5.
TIMBERS 1, NEW YORK CITY 0
Portland 1 0—1
New York City 0 0—0
First half—1, Portland, Valeri 17 (Mattocks), 44th minute.
Second half—None.
Goalies—New York City, Sean Johnson; Portland, Jeff Attinella.
Yellow Cards—Guzman, Portland, 22nd; Blanco, Portland, 27th; Sweat, New York City, 71st; Chara, Portland, 76th; Moralez, New York City, 88th; Valeri, Portland, 95th.
A—23,651 (28,940)
Lineups
Portland—Jeff Attinella; Zarek Valentin, Larrys Mabiala, Roy Miller, Vytautas Andriuskevicius (Lawrence Olum, 61st); Diego Chara, David Guzman, Sebastian Blanco, Diego Valeri, Darlington Nagbe (Jack Barmby, 86th); Darren Mattocks (Jeremy Ebobisse, 50th).
New York City—Sean Johnson; RJ Allen (Jonathan Lewis, 73rd), Frederic Brillant, Alexander Callens, Ben Sweat; Andrea Pirlo (Sean Okoli, 67th), Thomas McNamara, Khiry Shelton, Maximiliano Moralez, Rodney Wallace (John Stertzer, 83rd); Jack Harrison.