For the second straight night, Omaha’s offense struggled against first-place Iowa.

The Storm Chasers, handcuffed by rehabbing big leaguer Mike Montgomery in the series opener, managed a single run in six-plus innings against struggling starter Duane Underwood Jr.

The Cubs (19-10) extended their winning streak to five games with a 6-1 win over Omaha on Saturday at Werner Park. Underwood (2-3), who entered with a 7.77 ERA, scattered eight singles in his second win.

Iowa scored twice on Chaser starter Brian Flynn (0-2), on a MLB rehabilitation assignment, in the fourth to take the lead for good. Trent Giambrone doubled in a run, then scored on a wild pitch.

Omaha got its lone run in the bottom half when Cubs center fielder Ian Happ bobbled a ground-ball single by Bubba Starling, allowing Erick Mejia to score. Starling had three hits to raise his average to .356.

Iowa extended its lead with two runs off Arnaldo Hernandez in the fifth. Addison Russell’s sacrifice fly plated one. Phillip Evans followed with an RBI single. Dixon Machado added a solo homer off Hernandez in the sixth. Happ capped the scoring for Iowa, 10-4 on the road, with another sacrifice fly.

Omaha (13-16) fell to 4-9 at home, dropping six of its past seven at Werner.

Sign up for World-Herald daily sports updates

Get the headlines from Creighton, Nebraska, UNO, high schools and other area teams.