Boxing: Testing times ahead as Joseph Parker aims to fight his way back to the top

The dark sunglasses Joseph Parker wore on a clear and fine Cardiff day after his exertions of the night before couldn't hide his tiredness as he prepared to return to New Zealand, but a new target – to become a world champion again - is in clear sight.

The next few months will be crucial. How, once the 26-year-old returns to Auckland, will he cope with this unanimous defeat to Anthony Joshua, the first of his professional career, which relieved him of his WBO world heavyweight title?

He said all the right things in the immediate aftermath; disappointed but determined to come back bigger and better, and in theory this experience in front of a partisan and in some cases unpleasant crowd of 78,000 should make him a better fighter. Many of his extended team were too nervous to eat on the day of the fight but Parker was so relaxed he had a two-hour sleep in the afternoon.

And he has apparently already told his father, Dempsey, that the weight gains of the past won't happen this time after he worked himself into career-best condition during an intense three-month camp in Las Vegas.

After the Hughie Fury fight last year he ballooned to 121kg. He shed 14kg for this. More of that could shorten his career, so for him to recognise that is a positive, but the proof will be in the pudding, as it were.

The other aspect is that after earning more than $10 million for his efforts, the drive to get back to the daily grind of training may not be quite as appealing, but again, his message after the fight was "I'm going to be bigger and better. Sign me up."

He wasn't quite good enough on the night against a fighter in Joshua who keeps surprising with his ability to improve.

But Parker did show that he deserves to be on the same stage as Joshua. No matter what the doubters say, he is clearly an elite heavyweight in a very exciting division. Interestingly, he told trainer Kevin Barry that he thought former opponent Andy Ruiz Jr, whom he beat in Auckland to win the vacant WBO world title, punched harder than Joshua.

There are big opportunities ahead still, and Barry said before the team left for an overnight stay in London and a couple of long flights Downunder that he expects Parker to return to the United Kingdom to fight again as early as August.

"Over the next week we'll put a plan in place, but I think it's very important that over the summer here that we get Joe back in the ring – maybe in August," Barry said.

He added: "We're looking at all options but I would say with the experience we've made over the last three months, with the fan base and brand awarenesss that Joe and Duco have developed here in the UK, I think there is every chance our next fight will be here in the UK.

Parker was reluctant to talk to New Zealand media on his way to the bus but did say he was grateful for the support he had received from New Zealand and Samoa. Dad Dempsey said he was proud his son was the first man to go the distance against knockout artist Joshua.

Barry would have liked Parker to throw more combinations in an effort to take Joshua out of his comfort zone. When he did attack, Parker looked threatening, but the continued efforts of referee Giuseppe Quartarone to get in the way, and Joshua's defensive expertise, contrived to stymie that.

Parker was, Barry said, "a little emotionally tired … he apologised to me three or four times in the dressing room 'sorry coach'. I said 'mate don't be sorry, I'm proud of you. You fought a really good guy. We both know you maybe could have done a little bit more but we're still learning - you're still developing'. He said 'I'll come back stronger and I said, 'I know you will'."

Dad Dempsey and mum Sala smiled and waved from the back of the bus as they left for London; a case for Team Parker of farewell, but not goodbye.