Michael Phelps is in ominous touch, as the discussion around his potential inclusion for the 2015 World Championships intensifies.

The 18-time Olympic gold medal winner was banned from representing the United States at the pinnacle event, after he was found guilty of driving under the influence of alcohol in Baltimore in September.

Phelps was hit with a six-month ban in October, plus the additional sanction of world championships expulsion, but USA Swimming executive director Chuck Wielgus was recently quoted as saying the record-breaking Olympian could still compete at the worlds.

And Phelps' recent form shows the 29-year-old is still firing on all cylinders, after some impressive times at the American Short Course Championships in Austin, Texas - albeit unofficial ones.

Phelps completed the 100 metres butterfly in 44.91 seconds, the first time he has broken 45 seconds in the event, swimming the four laps in an exhibition prior to the finals taking place.

On Thursday, he also swam the 200m individual medley in 1:40.84 - 0.26secs behind his personal best, and what would have been the seventh-quickest time ever in the event were it not an exhibition.