Virves was ‘Mr Consistent’ on a day which truly tested the all-M-Sport Poland Ford Fiesta Rally3 field.
Posting second-fastest times on all but one of the day’s asphalt speed tests, Virves initially trailed championship leader Armstrong after the morning loop. However, Armstrong’s rally unravelled early in the afternoon when he pulled over to change a wheel at Mali Lipovec - Grdanjci.
The stop cost almost two minutes and promoted Virves into the top spot, but worse was still to come for the Ulsterman and he crashed out in the penultimate blast.
Virves faced increasing pressure from reigning champion Sami Pajari over the closing stages but held on by the skin of his teeth despite a last-minute puncture to end the day just 0.7sec in front.
"We have to be happy," said Virves. "It's our first time in such conditions and unfortunately we had a puncture on the last one.
"Let's see how the conditions are tomorrow with the cutting. I have no experience of these kinds of cuts, so it's not making it easy."
Pajari had a strong day and collected five valuable stage wins. He arrived back to service with a 19.4sec advantage over fellow Finn Lauri Joona.
Championship returnee Jean-Baptiste Franceschi was 2min 33.7sec further back after puncturing a tyre on SS5, while Kenyan youngster Mcrae Kimathi completed the leaderboard.
William Creighton was the only other non-finisher due to rear-end damage sustained in a crash at Stojdraga - Gornja Vas.
• Full coverage from the Croatia Rally will be available on WRC+ All Live here, including every stage broadcast as it happens as well as key interviews, features and expert analysis from the service park
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