Kevin Magnussen has expressed his sadness at missing out on a second season in F1 with McLaren as he faces a season on the sidelines.

After McLaren moved to sign the available Fernando Alonso for the 2015 season, Magnussen went up against the experience Jenson Button for the seat alongside him in the new Honda-powered MP4-30, the team waiting until December before opting for the Englishman.

The late decision meant Magnussen could not move to secure another drive in F1, the Dane accepting a reserve and test driver role with McLaren as a result.

Indeed, having turned heads during his rookie year - which included a podium finish in the season opening Australian Grand Prix -, Magnussen admits he was desperately disappointed to be dropped at this early stage in his career, but says he understood the decision.

"It was very frustrating," he said. "I desperately wanted to race this year and it has been tough. Immediately after learning I didn't have the drive, it was very sad times.

"I was looking forward to another year and continuing the progress. I felt I had a lot more to learn, so I have been massively disappointed, but I understand the situation.

"I can only say that I haven't given up and I am fully focused to getting back to F1, I just have to make the right choice and do the right things."

Magnussen got mileage in the troubled MP4-30 during pre-season testing and is on standby for the Australian Grand Prix in case Alonso - who was sidelined in the final test - is unable to compete.