Jenson Button has tipped McLaren-Mercedes to further close the gap on early-season F1 2011 pace-setters Red Bull Racing in this weekend's Chinese Grand Prix, despite a mixed opening day of practice in Shanghai.

Button lapped fourth-quickest in the morning session and third-fastest in the afternoon - on both occasions, one spot and around a tenth of a second behind team-mate and compatriot Lewis Hamilton - and he ultimately wound up less than three tenths adrift of Sebastian Vettel's benchmark for Red Bull. Despite both men alluding to some set-up issues, the 2009 F1 World Champion is confident that having already given RBR a fright in Malaysia, McLaren can turn the screw another notch in China.

"This morning was reasonably good and the car was working well - it's a good car to drive," reflected 31-year-old Button, who bought an antique sword with 'an amazing blade' in Malaysia. "For the afternoon, we tried a few things and didn't really improve the balance of the car, so we're going to look at why the changes didn't give us the improvement we expected.

"The car felt reasonably strong on the 'Prime' tyre, but less so on the 'Option'. It's not been a perfect afternoon, but we have a lot of information on the changes we made, so we can hopefully work on improving the set-up tomorrow. It's not as hot as it was in Malaysia, so I don't think the tyres will be as much of an issue to look after as they were in Malaysia. If we sort out the balance tomorrow, we'll be closer to Red Bull.

"If we get a nice clean race start, we could have a fun race and I think the pace [between McLaren and Red Bull] will be reasonably similar. I finished three seconds behind [Vettel in Malaysia]; he definitely slowed down at the end, but I don't think he did on every lap - our pace was quite similar. I think we can make more headway than Red Bull, because of not really completely knowing our car and not having the perfect set-up over the past couple of races. Also, we have some updates here; I don't know if Red Bull has."

Hamilton echoed many of his fellow title-winner's sentiments, and is desperate to battle back with a strong result in Shanghai - where he triumphed in 2008 en route to his first and thus far only drivers' crown at the highest level - following his crushing disappointment at Sepang.

"It's been a busy day today," acknowledged the 14-time grand prix-winner. "The car wasn't too bad at the end of this afternoon's session, and I was able to get a decent lap time despite not feeling totally comfortable with it. We've been struggling a little bit with the set-up; it doesn't feel like the car's performing in all the areas we expected. We need to see whether the issue with the car's balance is down to the upgrade or just an unsatisfactory set-up.

"It does feel like we've found some further improvements since Malaysia, though, and we'll spend this evening looking at what elements of the new package we choose to take forward into the rest of the weekend."

"It was a productive day," concluded the Woking-based outfit's team principal, Martin Whitmarsh. "We spent the morning conducting aerodynamic tests, and we limited each driver to just one set of 'Prime' tyres. That helped us to draw some productive conclusions as we evaluate this weekend's suite of upgrades and decide what to progress and what will need more development.

"This afternoon was a bit more frustrating - neither Lewis nor Jenson really found a satisfactory balance. They didn't feel as comfortable as we hoped they would be, but we've got some very good information and, as always, I think our engineers will take every opportunity to look over that and turn it into something productive for tomorrow."