Michael Phelps and his rival Ryan Lochte could face each other up to six time at the world championships in Shanghai.

Shanghai – Michael Phelps and Ryan Lochte might be buddies outside the pool, but once they hit the water they become rivals.

At the 14th aquatics world championships in Shanghai a showdown is looming in the Oriental Sports Centre as they have both entered the 200-metre freestyle and the 200-metre individual medley events – making six direct encounters possible.

On Monday, the two, who are both 26, were paired against each other in the heats of the 200-metres freestyle – but not only that, they were actually in lanes next to each other.

Lochte won the first encounter, recording the fastest time of all the swimmers of one minute 43.34 seconds, beating Phelps' time by 0.64 seconds.

Lochte admitted that he had not set out to swim such a quick time. “I kind of just wanted to have an easy swim but Michael was next to me and we were pushing each other. It was rough.”

Later Monday, the two will face each other again in the semifinals and – if all goes according to plan – they will then face their winner-takes-all showdown in Tuesday's final.

“Ryan and I are going to be in the second heat tonight (Monday), so we will see what it’s going to take to get top eight.

“Before our heat I told him we have to go 47 to make it back. I did not think I was going that fast, but I am happy with that though, feeling how I did,” said Phelps.

In many ways the two could not be more different.

Phelps is the dedicated professional, who eats, sleeps, dreams and thinks swimming, while Lochte is – as he puts it himself – just another guy who happens to swim fast.

In interviews his most common phrase is “whatever” and his biggest disappointment at the Beijing Olympics was that US team officials refused to give him permission to ride down the Great Wall on his skateboard.

When asked before the Olympics how he would feel if he failed to win as many medals as he expected, he said that it would make no difference.

“Whatever, I'll still have my skateboard, my surfboard and the waves,” he said at the time.

Lochte admitted to journalists in Beijing in 2008 that he ate only at McDonalds during the Olympics.

Possibly all of that is one of the reasons why Phelps is the most decorated Olympian of all time, winning 14 gold medals (eight alone in Beijing) and two bronze. He also has an astonishing 27 medals from the long-course world championships, 22 of which are gold.

Compared to Phelps, Lochte must seem like the poor cousin.

He has three Olympic gold medals, one silver and two bronze, as well as seven gold, three silver and four bronze from the long-course world championships.

But Lochte seems to be the man of the moment, taking his swimming more seriously and getting the results.

While Phelps was struggling with his motivation – and thereby his form – last year, Lochte was the only swimmer to break an individual world record and picked up six gold medals in the short-course world championships in Dubai in December.

When asked about at the start of the competition in Shanghai whether –given Phelps' record – he thought he could beat him, he said that he could.

“What Michael achieved in Beijing was amazing. But it is also history. Now is another time and that is what matters.”

Judging by the first of their expected six showdowns, he may be right. In the words of Bob Dylan, the times they are a-changin. – Sapa-dpa