Group leaders Mexico, who host the United States on Sunday, beat Honduras 3-0 to record their fourth consecutive victory and cement top spot on 13 points. Oswaldo Alanis put the Mexicans ahead after 35 minutes before Hirving Lozano Raul Jimenez added second-half goals.
Costa Rica are in second place on eight points after drawing 0-0 with Panama, who trail the United States by a point.
In Colorado, the United States struggled to get going in the first half and almost fell behind when the visitors' Kenwyne Jones smacked a header off the bar, but they got the breakthrough after 52 minutes when Pulisic slid in to stab home a low cross from DeAndre Yedlin.
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Pulisic doubled his tally 10 minutes later when he ran on to a perfectly weighted pass from Jozy Altidore and slotted past goalkeeper Jan-Michael Williams. It was Pulisic's fourth goal in his last four games for the national side.
"It took us a little while to get going but once we'd worn them down our quality showed," Pulisic said in a televised interview.
The top three teams from CONCACAF qualifying earn an automatic spot at the 2018 finals in Russia, while the fourth-placed team go into a play-off against a side from the Asian confederation.
(Writing by Andrew Downie; Editing by Peter Rutherford)
