KARACHI (Reuters) - In the currency market, the rupee firmed marginally from its record low of 85.80 to the dollar the previous day, but dealers said the local unit was likely to remain under pressure. The rupee ended at 85.70/77 to the dollar, compared with a record closing low of 85.75/80 on Monday. Dealers also said exporters were holding on to dollars as they expect the rupee to weaken further.