* Dollar remains close to 2018 lows * Sterling on edge heading in to crucial Brexit weekend * Investor take shelter in safe haven Swiss franc * Graphic: World FX rates in 2020 tmsnrt.rs/2RBWI5E LONDON, Dec 11 (Reuters) - Pressure was easing on the dollar on Friday, with the currency set to snap out of three straight weeks of losses while sterling still suffered due to fears a post-Brexit trade deal might not be reached before the end of 2020. Overnight, hopes of a global economic rebound and a fading pandemic in 2021 saw investors taking bets on riskier currencies linked to rising commodity prices. Surging iron ore prices had lifted the Australian dollar to a two-and-a-half year high of $0.7542. A nine-month peak for oil prices also had pushed the Canadian dollar to its highest since 2018. But at 0900 GMT, pressure was easing on the greenback, which was back up 0.2% against a basket of major currencies, trading at 90.867 but still not far from a two-and-a-half year low of 90.471. The euro was taking a breather, down 0.12% against the dollar after Thursday’s gains when the ECB announced a new round of stimulus in line with markets expectations and EU leaders reached a compromise over a pandemic aid package. The common currency has soared 15% from three-year lows at the height of the March markets panic and has added nearly 2% in two weeks since finally breaking $1.20 after multiple attempts. Sterling on the other hand was still under pressure in early trading, down about 0.75% at $1.3193 ahead of a weekend of brinkmanship as British and EU negotiators have been told they have until the end of Sunday to decide whether a trade deal is possible. The pound has slipped 1.8% this week as British and European leaders have expressed doubts that they will be able to salvage a deal. But options market moves show traders bracing for chaos, with one-week implied volatility at a new eight-month high and the premium of sterling puts to calls near its highest since April as investors pay up for downside protection. “In addition to Sterling the Swiss franc is the main victim of the rising Brexit uncertainty - the difference being that it is under appreciation rather depreciation pressure, which is unlikely to please the Swiss National Bank though”, Commerzbank analyst Thu Lan Nguyen. The Swiss franc is trading at a 2015 high against the dollar, and was rising 0.28% at $0.8854. (Reporting by Julien Ponthus; Editing by Angus MacSwan)