Nico Rosberg tells Lewis Hamilton "keep it clean" NICO ROSBERG has urged team-mate and rival Lewis Hamilton to keep it clean in their Formula 1 world title showdown in Abu Dhabi tomorrow. The warning came as Hamilton set the fastest times in both practice ­sessions yesterday ahead of their end-of-season clash at the Yas Marina circuit, dubbed the "Duel in the Desert." It was a reminder from Rosberg to Hamilton to play fair, despite the contentious issues that may have occurred between the duo over the course of the past few months. In particular, Rosberg's manoeuvre in qualifying in Monaco when he appeared to make a mistake before reversing back on track, so ensuring himself of pole position in the process, has been deemed deliberate by many seasoned observers. A few months later at the Belgian Grand Prix, Rosberg deliberately opted not to pull out of a crash with Hamilton, who was later forced to retire with damage sustained in the incident. With Hamilton holding a 17-point lead over Rosberg, he could ­easily ­decide to take matters into his own hands, as has occasionally been the way in F1 in the past. Asked whether it would be a totally clean fight, Hamilton replied: "Yeah, I don't really know what else to say. That's how it's been. You have to go into the weekends believing that's going to be the case. Pushed as to whether any conversations between the duo would be necessary ahead of the race, Hamilton initially issued a stern "No." When it was suggested to Hamilton that it would be unnecessary or they ­already had an understanding, he added: "We don't need to. It's already been ­discussed at the beginning of the season and several times through the season, and particularly after Spa. There's no reason to revisit it. We're not children, we should know what is wrong and what is right. Asked for his thoughts, Rosberg made clear it is down to Hamilton to stay on the straight and narrow. ­Rosberg said: "Lewis can do something to keep it clean which is drive cleanly himself. It's not like he can't do anything. Of the two, Rosberg appeared the more composed, albeit with Hamilton insisting he was not feeling the heat. "In terms of the pressure, I don't ­particularly feel any," said Hamilton. I've had plenty of experience through my racing career - 15 odd years I'd say, actually it might be 20 years of racing - to be prepared. There's no special recipe for it. A top-two finish, regardless of the controversial double points on offer this weekend, will guarantee Hamilton the title. Given Mercedes have scored one-twos in the last six races it would appear all that can stop Hamilton is ­either an accident or a technical issue. In practice yesterday, Hamilton did all that was asked of him as he topped the timesheet at the end of both sessions, with Rosberg second best. Not for the first time this campaign, no one could hold a candle to the duo. At the conclusion of the first 90-minute session, in particular, the margin from Hamilton to Ferrari's Fernando Alonso in third was a staggering 1.7secs following soft-compound tyre runs. With Pirelli's supersoft rubber given an outing in the second session, the margin of dominance was at least narrowed. Hamilton finished a slender 0.083secs clear of Rosberg, with Kevin Magnussen in his McLaren the best of the rest at nearly three quarters of a ­second off the pace. Red Bull's Sebastian Vettel, now ­confirmed as a Ferrari driver for next season, and Williams" Valtteri Bottas, also managed to finish within a second of Hamilton. Red Bull's Daniel Ricciardo was sixth ahead of Kimi Raikkonen in his Ferrari, with McLaren's Jenson Button eighth, albeit late on track given an earlier technical fault and managing only 23 laps, with Toro Rosso's Daniil Kvyat ninth and Felipe Massa tenth.