Diriba, who placed fifth in the 5,000m at the 2013 Moscow World Championship, shattered Rosemary Wanjiru's previous fastest time of 2017 by six seconds last night. Wanjiru set her time of 8:51.61 in Tokyo in April.
Diriba edged runner-up Kenya's Sheila Chepkirui who finished in 8:45.94. Ethiopian Gotytom Gebreslase was well back in third at 8:58.88.
Ethiopian long distance runner Muktar Edris also put on an incredible performance in the men's 5000m. He won in a time of 13:01.04 just off Mo Farah's world best so far in 2017 of 13:00.70 set last weekend in Eugene, Oregon. Farah won the 5,000m and 10,000m at both the 2012 and 2016 Olympics.
The Boston Games end Sunday with the sprint events, long jump and pole vault.