If San Diego FC had any doubts that staying on top of the Major League Soccer Western Conference standings is harder than getting there, the 11th-place Houston Dynamo erased them Saturday night. The visiting team, attired in bright orange, performed much better than its minus-6 goal differential and took a 4-3 victory before an announced crowd of 28,231 in Mission Valley. Cranking up an offense that led the MLS in goals and assists, San Diego FC took leads of 2-1 and 3-2 but saw its five-game winning streak end and walked off with its first home loss since April 26, a 3-1 decision against Real Salt Lake City. Goals by Milan Iloski, Luca Bombino and Onni Valakari had SDFC ahead going into the 85th minute. From there, the first-year MLS club made two critical defensive errors. A poor pass from the rookie Bombino toward SDFC goalkeeper CJ dos Santos led to a collision that bloodied dos Santos’ nose. Because dos Santos initiated the contact in the box, Houston was awarded a penalty kick. Argentine forward Ezequiel Ponce, who’d inadvertently elbowed dos Santos in the nose, roofed the shot down the middle, tying the score in the 87th minute, The second defensive error came nine minutes into stoppage time. All but rolling a red carpet out, a cluster of SDFC players allowed Dynamo center back Ethan Bartlow to stroll toward the box with the ball. Batlow threaded a through ball to Ponce, who one-touched a left-to-right shot past dos Santos, sending Houston toward the win. Iloski, the sure-footed MLS rookie from Escondido, scored his 10th goal in just 14 matches this season off a headed pass from Valakari, completing a sequence begun by Bombino’s pinpointed crossing pass after the 18-year-old collected a long pass from Anders Dreyer. The clean finish by Iloski moved him past Dreyer for the team lead in goals. Bombino, obtained in February from LAFC, left-footed a backward header by Tverskov, tying the score at 2-2 early in the second half. A delicate chipped pass by Hirving “Chucky” Lozano, who entered in the 56th minute, in his second game since suffering a second hamstring injury this season, led to SDFC’s final goal — Valakari’s deflection of Dreyer’s shot in the 67th minute. San Diego FC will resume play Saturday with a road match against Chicago. Before then, coach Mikey Varas and squad will attempt to learn from several defensive breakdowns that, exploited by opportunistic Houston, showed how vulnerable a first-place team can be.