Seventy-eight players, half the field, were still on the course when play was called for the day after thunderstorms stalled over the area.
Defending champion Casey Watabu of Kapaa, Hawaii, parred his first hole before play was suspended on the 7,048-yard Cantigny Golf.
Lucas Lee, a sophomore at UCLA from Brazil, and Nicholas Becker of Boise, Idaho, were one stroke behind Harrell, a senior at Alabama, and Rask, a senior at Minnesota.
The first round was to be completed Tuesday morning with the second, and final, round of medal play scheduled to start in mid-afternoon.
The top 64 after stroke play advance to match play.
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