There is nothing Joseph Schooling cannot achieve if he puts his mind to it, says his former coach Sergio Lopez, as the Singaporean gears up for this week's Swimming World Championships.

The 22-year-old stunned the world with his 100m butterfly victory at last year's Rio Olympics and is seeking to add the world title in the same event.

He is also targeting a gold medal in the 50m fly. Prior to his bronze in the 100m fly at the 2015 World Championship in Kazan, Russia, no Singaporean had returned from the elite competition with a medal.

Lopez, who mentored and trained Schooling during their time together at The Bolles School in Florida, believes Schooling has nothing to prove to anyone.

The Spaniard was the Republic's national head coach from 2014-2016 before his current role as associate head coach at Auburn University in the US.

He told The Sunday Times: "Joseph has a target in his back and he needs to be able to understand that it's normal.

"He should place the pressure on the other swimmers and keep looking forward to getting stronger and smarter in and out of the water.

"He has to understand that the pressure is not on him, (but) on the guys that want to beat him. If he trains to the best of his ability and he gives his 100 per cent, then everything else is out of his control."

What Schooling has command of is how fast he can go in the water. After a lacklustre series of performances in the first half of 2017 - he attributed it to losing his focus following his historic achievement in Brazil - he appears to be peaking at the right time.

He told ST yesterday: "It's always hard to maintain when you're at the top but that's where I want to be. I want to be No. 1 in the heats, semis and finals."

He clocked 50.96sec in his pet event earlier this month at a Texas meet. It was the year's second-fastest time - behind American rival Caeleb Dressel's 50.87sec last month - and almost a second faster than Schooling's previous season -best (51.82sec) also in June.

Besides Dressel, there is also the threat of South African Chad le Clos, seeking his third straight 100m fly world crown after wins in 2013 and 2015 and Lopez's dark-horse pick Laszlo Cseh, the veteran Hungarian.

Schooling said: "There's no Michael (Phelps) or (Ryan) Lochte here but there are still plenty of guys who are tough competitors."

He has gone below 51 seconds on three previous occasions: the 2015 Worlds (50.96sec), and in the semi-finals (50.83sec) and final (50.39sec) in Rio where he set an Olympic record.

Schooling starts today with the 50m fly heats, and Lopez expects a solid outing from his former pupil.

He said: "Last year he never went under 51sec before Rio unshaved (referring to Schooling's recent swim in Texas in which he did not taper specifically for).

"In Kazan, he was 50.9sec and everyone thought that was unbelievable.

"Now, if you were Joseph, would you have doubts about your ability to do it?"

Schooling will also compete in the 100m free and 200m fly. Compatriot Quah Zheng Wen, 21, will swim in the 50m, 100m, 200m fly and 100m and 200m back events.

Quah reached the 100m and 200m fly semi-finals in Rio, narrowly missing out of a last-eight spot in the 200m fly by 0.08sec.

His personal best is 1:56.01, and while his quickest this year was 1:57.91 at last month's Singapore National Championships, national training centre head coach Gary Tan expects him to go much faster in Budapest.

Tan has worked with Quah since he was 13 and was hopeful Quah could post a high 1:54-1:55 and make the semi-finals.

While Quah remains a work in progress, Schooling carries the weight of a country's expectations.

It can be unrealistic at times, said Lopez, a bronze medallist at the 1988 Olympics, but Schooling has proven himself on the big stage.

"Believe in him," added Lopez. "He wants to do it."