Brad Ziegler and the Arizona Diamondbacks are treading water in the NL West.Paul Goldschmidt hit a two-run home run in the first inning and Trevor Cahill and three relievers made it stand up in Arizona's 2-1 win over Los Angeles on Monday night.With Los Angeles' fourth loss in a row and the Diamondbacks third straight win, the Dodgers' magic number to clinch the NL West remains four.The win also means the Dodgers will need to win the final two games of the three-game series to celebrate on the Diamondbacks' home field."Until we are mathematically eliminated we have to win every night," Ziegler said. "We've got to go at it, especially when we are playing the team we are chasing.Los Angeles has lost 11 of 12 but the Dodgers' once 13 1/2-game lead over Arizona only has shrunk to 9 1/2 with 12 games to play.The Diamondbacks are only in slightly better shape in the NL wildcard race, trailing the trio of Pittsburgh, St. Louis and Cincinnati by eight games with Washington three games ahead."We can't worry about what they are all doing," Ziegler said. "We have to go out and play our game."The Diamondbacks managed only two hits against Los Angeles starter Hyun-Jin Ryu, marking the third time in club history they have won with two hits or fewer."We were fortunate but sometimes you have to win 2-1 with two hits," Arizona manager Kirk Gibson said. "We got two hits but we made the most of them."Goldschmidt raised his NL-leading RBI total to 116 with his 33rd home run off Ryu (13-7). Goldschmidt has homered in each of his last two games after an 83-at-bat drought."He threw a fastball first pitch and I was looking for something over the plate," Goldschmidt said. "(Ryu) pitched great."Ryu (13-7) went the distance for his second complete game. He walked one, struck out four and retired 23 of the final 24 batters he faced."I threw 100 pitches but that one pitch was the decision-maker of the game," Ryu said. "It was an error on my part. I believe no matter how good a pitch it was. If it is a home run, it's a mistake."Cahill (7-10) won for the fourth straight decision, holding Los Angeles to one run on two hits over 5 2/3 innings.Ziegler pitched the ninth for his 11th save but not without some drama.Michael Young hit a pinch-hit single to center and Skip Schumaker singled to left. Juan Uribe tried to bunt the runners over, but Ziegler fielded the ball and threw to third to force Young for the first out. Nick Buss hit a soft bouncer to first for the second out as the runners advanced.Dodgers manager Don Mattingly then sent up Matt Kemp, who was activated off the 15-day disabled list earlier Monday. Ziegler got ahead 0-2 on two swinging strikes, wasted a pitch and then struck out Kemp on a lunging swing at on a curveball well low and outside.."I've faced him a lot even before I got to Arizona, facing him in batting practice," Ziegler said. "I know what he'd trying to do and he knows what he wants to do against me. Luckily, I came out on top tonight."Cahill was nearly untouchable over the first five innings, allowing only a single by Punto to start the game and a two-out walk to Puig in the first before retiring the next 13 in a row. But the right-hander quickly ran into trouble in the sixth with the Diamondbacks still holding a 2-0 lead.Cahill walked Ryu, Punto doubled to the wall in left-center and Mark Ellis walked to load the bases. Cahill retired Adrian Gonzalez on a line drive to left and the runners held, but he then walked Puig to force home Ryu and cut Arizona's lead to 2-1.Josh Collmenter came in on a double switch and escaped the jam, striking out A.J. Ellis and getting Schumaker on a broken-bat grounder to second to leave the bases loaded."He's done that in the past," Gibson said of Cahill. "He just starts to lose it. You could just see he was aiming the ball."NOTES: Goldschmidt is tied with Reggie Sanders for eighth place on Arizona's single-season home run list and moved into sole possession of third place in RBIs behind Matt Williams' 142 in 1999 and Luis Gonzalez's 142 in 2000. ... Cahill has not pitched past the sixth since August 22, a span of four starts. ... Ryu's other complete game came on May 28 when he threw a two-hit shutout against the Los Angeles Angels.