Haas stopped Sam Querrey 6-4, 6-4 in just 62 minutes. Querrey fired off 11 aces and won nearly two-thirds of the points on serve but didn't manage a break opportunity against Haas.
Haas lost only 154 points on 10 games serving and was 1-for-2 in each set in break chances.
Isner, who had 29 aces, got past Santiago Giraldo 4-6, 7-5, 7-5. Isner dropped his serve once, which cost him the first set, but didn't see a break point in the second and saved all three of the break chances for Giraldo in the third.
Gale Monfils defeated Tatsuma Ito 6-3, 6-2 in 53 minutes, taking 60 percent of the points in the match. Marcel Granollers beat Janko Tipsarevic 6-4, 6-4 and earned a second-round spot opposite top-seeded -- but now No. 2-ranked Novak Djokovic.
Djokovic is the tournament defending champion.