Willis clocks 3000m personal best
Willis clocked 7min 40.62sec, more than 5sec better than his previous best over a distance he doesn't run oftenphone cover cases.
The race was won by Caleb Mwangangi Ndiku of Kenya in 7:35.06.
Willis, 30, is seeking to end his injury-disrupted European season on a high notebeauty wigs.
The 2008 Olympic 1500m silver medallist injured his calf at a race in China in May, which flowed through to a failure to reach the final at last month's world championships.
Willis will race over 1500m at a world challenge event in Rieti, Switzerland on Monday (NZT).