Tyson Ross is headed to his first All-Star game and receives the opportunity to justify his selection to the National League team when the San Diego Padres visit the Colorado Rockies on Tuesday in the second contest of a three-game set. Ross owns a 7-8 record and was a surprise choice to the squad with San Diego closer Huston Street viewed as the club's probable selection. Colorado lost for the 18th time in 21 games and fell into last place in the National League West with Monday's 6-1 loss.Padres third baseman Chase Headley has been a major disappointment most of the season but recorded his second four-hit outing in a span of four games in the opener. Headley entered July with a dismal .201 batting average but has raised it 28 points by going 12-for-26 over the last six games. The slumping Rockies have lost 16 of their last 21 games at Coors Field and have scored just five total runs over their last four home losses.TV: 8:40 p.m. ET, FSN San Diego, ROOT (Colorado)PITCHING MATCHUP: Padres RH Tyson Ross (7-8, 2.93 ERA) vs. Rockies LH Franklin Morales (4-4, 5.51)Ross has allowed two or fewer earned runs in 12 of his 18 starts after entering the season with a 9-26 career record. He tossed a three-hit shutout against Cincinnati in his last turn after going 0-4 over a five-start stretch. Ross is 0-2 with a 2.75 ERA in five career appearances (three starts) against Colorado. Morales has been prone to the long ball and has allowed 17 in just 81 2/3 innings. He is making his 13th start of the campaign and gave up two runs (one earned) and four hits in a five-inning no-decision against the Los Angeles Dodgers in his last turn. Morales is 1-2 with a 4.87 ERA in 15 career appearances (two starts) against San Diego and the victory came on April 17 when he limited the Padres to one run and four hits in six innings.WALK-OFFS 1. The Padres are 28-4 when scoring four or more runs.2. Colorado 3B Nolan Arenado (finger) is 2-for-19 in five games in his return from spending five-plus weeks on the disabled list.3. San Diego C Rene Rivera reached base four times on two hits and two walks on Monday and is 5-for-9 in his last three games.PREDICTION: Padres 9, Rockies 5