Paul di Resta prepared for a fight while Bruno Senna is ready to go

MELBOURNE // Battling against second-season syndrome, Paul di Resta, the Scottish driver with Force India, said he is feeling even more pressure this year with the competitiveness in the middle of the Formula One field having increased considerably.

Pre-season testing in Spain proved little, but one of the few patterns that emerged is that the spread between teams fighting in the midfield has closed up significantly.

England-based Force India enjoyed a strong finish to the 2011 season, with both cars claiming points at the final two races of the season in Abu Dhabi and Brazil, but Di Resta, who managed eight top-10 finishes last year, expects an ever-tougher contest this season.

"I believe it will be more bunched up, and everybody will need to raise their game," he said ahead of Sunday's Australian Grand Prix.

"I think what we'll see is that if someone is having a very good weekend, there will be a bigger benefit and if someone's having a bad weekend they'll be in more trouble. We'll see where we are Saturday afternoon, but it looks a lot tighter, so it's crucial to get everything right."

While Di Resta acknowledges feeling the pressure, Bruno Senna - making his debut for Williams this weekend - says he has never started a season so relaxed.

Following a year with troubled backmarkers Hispania in 2010 and joining Lotus-Renault mid-season to contest the last eight races of 2011, Senna said he is ready to reap the benefits of a full, positive winter.

"It is a very different beginning to everything I have done before in Formula One, and I feel much more relaxed than I did the previous two times," he said.

"But, at the same time, I feel much more excited because everything is a bit more straightforward - so it is very interesting and I am looking forward to practice."

Senna - whose uncle Ayrton was a three-time world champion - said this season offers the first fair opportunity to judge him against his racing rivals.

"This is the first time I am going to have the same preparation as the other guys, and my pre-season has been very strong because we managed to do so many miles," he said.

"[Two seasons ago] was a very tough one, and I barely survived that, but last year was fairly good.

"It was important to show good potential and show some good strong performances, and that has enabled me to be here now."