Mo Farah already has one eye on next year's World Championships and the other on the 2016 Olympics as he looks to put his "toughest year" behind him.

A difficult 2014 has seen the Olympic superstar disappoint on his London Marathon debut before illness forced him out of the Commonwealth Games.

He bounced back with double gold in the 5,000 and 10,000 metres at the recent European Championships in Zurich to set himself up for a brighter 2015.

"It's been an up and down year but I'm back on top now," said Farah.

"It's been very difficult, from the London Marathon, where I wanted to do better, to then getting ill and missing the Commonwealth Games. It's been a struggle but now I'm back.

"I learned a lot from the marathon and I'm not ready for that yet, but after Rio we'll try again - but for now I'll concentrate on the track.

"It's been the toughest year of my career for sure, certainly the toughest I've had for many years. I hadn't been injured for many years and this season was tough.

"I'm already looking ahead to Beijing (World Championships) but in long-distance running you can only take one year at a time, you can't look two years beyond. But yes, it's obviously there."

Much was made of the double Olympic champion missing the Commonwealth Games in Glasgow this summer but he accepts the spotlight he is under.

"There's always pressure and as an athlete you put more pressure on yourself," he said ahead of Sunday's Sainsbury's Birmingham Grand Prix.

"There's never going to be the level that there was at the London Olympics, so you just get on with it."

After Beijing next year, Farah is desperate to match his achievements of 2012 at the Rio de Janeiro Olympics and he admits that competition takes precedence in the long term.

"Rio is the most important thing," he said. "If you ask any athlete 'Olympics or Worlds?' anybody would say Olympics.

"That's the big one. But at the same time you still have to go out there and deliver at the World Championships too."

:: Watch the world's best athletes including Mo Farah, David Rudisha, Christine Ohuruogu and Shelly-Ann Fraser-Pryce at the Sainsbury's Birmingham Grand Prix on 24 August. Tickets via