The only car to lap slower was the sole Spyker-Ferrari of Adrian Sutil.
Before the rain came, team mate Christian Klien managed to put a lap of 1:24.227, 0.707s faster than Barrichello, and fast enough to place him 13th, still 1.593s behind pace setter Pedro de la Rosa in the McLaren.
With the drivers struggling to get any significant pace at any test this year, there's some positives in the fact that the car is at least reliable.
Reports from the track suggest that Honda are struggling more than other teams to adapting to the new Bridgestone tyres, despite a front suspension system that allows increased adjustment levels from the perceived norm.
With temperatures at recent tests being lower than usual, along with surprisingly frequent rainfall, time is running out for Honda to resolve these issues.
Testing is scheduled to continue until Wednesday, although weather conditions may lead to the teams stretching this until Thursday. After that, the team heads to Bahrain for their penultimate test before the season begins.
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