Forex traders said the principal driver behind the rise in Brent crude prices is the uncertainty over the Strait of Hormuz. At the interbank foreign exchange, the rupee opened at 95.40 before slipping further to 95.42, down 6 paise from its previous close. On Tuesday, the rupee declined 6 paise to settle at 95.36 against the US dollar. Brent crude, the global oil benchmark, was trading higher by 1 per cent at USD 89.80 per barrel in futures trade. "Rupee opened at 95.42 with oil prices slightly down at USD 89.36 per barrel, while the dollar index was at 99.83 virtually unchanged.