Rehberg did not advance to the final after her 15th-place performance in the third of three heats in the event.
Her time of 9:51.73 ranked her 44th among the 52 competitors.The third heat produced the slowest times among the three with just one additional runner outside of the three automatic qualifiers advancing. Six competitors from heat two and five from heat one moved on to the final.
Rehberg's German teammate Gesa Felicitas Krause and all three American performers (Emma Coburn, Colleen Quigley and Courtney Frerichs) were among the 15 qualifiers for the medal heat.
Two other former Gaels compete in Rio -- Leonard Korir in the men's 10,000-meter final Aug. 13 and Anna Holm Baumeister in the women's marathon Aug. 14.
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