Cal Crutchlow spent most of his final race as a full-time MotoGP rider fighting in the thick of the top six at Portimao on Sunday.

But with his rear grip waning the LCR Honda rider eventually made one mistake too many, "flying off the track" into Turn 1 and losing touch with the group fighting for fourth place.

The Englishman eventually finished at the back of that pack, in 13th.

Crutchlow, who has taken 19 podiums and three MotoGP wins during his career, labelled the result "disappointing" but "I never gave up, I went for it and that's the way it goes."

"I'm disappointed about my result because I felt like I could have held a good position, but I had a really big rear tyre drop, maybe a little bit because of the mapping and electronics at the start of the race - I was probably using too little traction control," Crutchlow said.

"But evidently, I continued to fight and I flew off the end of the track at 300 a few times into Turn 1! I never gave up, I went for it and that's the way it goes.

"Overall, I'm happy to finish [my career]. I'm done, honestly.

"I still tried my best but I'm done with full-season racing so it was nice to go out today and still be able to fight with some of the best riders in the world. The guys I was battling with have won races this year and been on the podium many times.

"I'm also pleased to have finished the race because I started my career with a crash and I could have quite easily finished my career with a crash!

"It's emotional to stop but I gave my all in the race and that's all I could ask of myself, as always."

Outstanding Oliveira, shocking Suzuki & a rickety Rossi | Portuguese MotoGP Winners & Losers

Crutchlow's teams have spoken with pride about how, after returning from a fast accident and sometimes in pain, he would go straight back out and – from the data – they could see he was pushing at 100% again straight away.

Such determination and the burning desire to prove his doubters wrong has taken Crutchlow to heights that he freely admits talent alone would not have taken him, not to mention fuelling memorable rides while injured.

But now is the right time to "step back and watch my mates and the young guys go for it".

"I feel a [sense of ] relief. I feel, as I said, I'm done," explained the 35-year-old. "I believe I've won a race in every championship I've been in. I couldn’t have done any more, honestly speaking, with my talent alone.

"I've always been the first guy to say that it was my determination that brought me through most of racing. And maybe not being the most talented made me continue longer and want it more.

"I always said I would stop and retire when I got up in the morning and never had the motivation. But I still get up in the mornings and still have the motivation to go on my bike and train etc. It's just I can't compete at the level I want to compete at anymore. It's as simple as that.

"Obviously I'll continue to ride a motorcycle next year with Yamaha [testing] but it's been a massive part of my life and, yes it's come to an end, but I'll still actively be involved.

"I look forward to watching the races from home and not being in them all the time with the worrying and stress, the build-up and the travel. It sounds like I'm complaining about it but when you get older things like that make it more difficult."

The highlight of Crutchlow's career was his Brno 2016 MotoGP win, the first premier-class victory by a British rider since Barry Sheene in 1981.

Further victories followed at Phillip Island 2016 and Argentina 2018, when Crutchlow also became the first Briton to lead the premier-class standings since Sheene in 1979 and first satellite rider since Sete Gibernau in 2004.

"I've had a great time, a good career that I've enjoyed," Crutchlow said. "It was nice to be that British winner because I felt that I put the work in to be able to do it.

"So now I can take a step back and watch my mates and the young guys go for it."

Crutchlow is a mix of contradictions. The fearless motorcycle racer (who fell 26 times during the 2016 season) combined with dedicated family man. Confident and outspoken, yet at times sensitive to criticism and insecure. Combative and quick to argue, but highly respected by his rivals.

Despite the physical pain Crutchlow endured this season, including surgery on his wrist and arm, plus damage to his ankle and shoulder, being separated from his wife and daughter perhaps proved just as tough.

"I'm still fast, but week-in, week-out, with regards to this championship this year, it made me realise that I want to be at home, I want to do different things in my life," Crutchlow said, before describing his post-race plans as: "Go back home to the Isle of Man and spend some time with the girls.

"I haven't seen Luce a lot this year, Willow hasn't seen her Dad. Obviously, the good thing for me is that I've always spent all my time with Luce, even when I raced 10 years ago, we always travelled together, and in the last four years since Willow was born we brought Willow with us as well.

"So it's been a strange year and I can't wait to get home to them."

Making his MotoGP debut with Tech3 Yamaha in 2011 on the back of a World Supersport title and WorldSBK race wins, Crutchlow claimed six podiums on the M1 and then one rostrum during his season at the Factory Ducati team before arriving at LCR Honda in 2015.

“It is a hard day for us because Cal Crutchlow has definitely been the most important rider in the history of the LCR Honda team," said team boss and former racer Lucio Cecchinello. "He has been the rider that has ridden for the longest consecutive period of time with us and, because of this, he is part of our family.

"Cal brought 3 stunning victories and 12 podiums in total to LCR. We were also able to support Honda by adding crucial points for the Constructor World Championship Title and with him, we won Best Independent Team in 2016. What Cal has done for the LCR Honda Team is simply extraordinary.

"During these six seasons together, we’ve had also some tough moments, difficulties, injuries… but this is all part of this incredible sport that gives us a lot of emotions, happiness and adrenaline. On the other hand, of course, it also gives us many headaches, fears and stress. If everything were smooth and perfect, we wouldn’t enjoy our job as much. I think that it is because of these emotions and mixed feelings, that we love MotoGP.

"Cal Crutchlow will always be part of our family. We wish him all the best in his professional future and in his private life with Lucy and Willow.”

Crutchlow will start his new role as Yamaha test rider at Sepang next February and may yet make a race appearance as a wild-card or replacement rider.