Under a year ago, Massu was playing Challenger tournaments in a bid to find some form and improve his ranking.
World ranking: 12
Australian Open best:
1st round (2002, 2001)
2002: 1st round
2001: 1st round
Now, he finds himself seeded at the first Grand Slam of 2004 after a stunning second half of last season.
The turnaround in fortunes began in July when he won the Amersfoort claycourt tournament in Holland and the following week reached the final in Kitzbuhel.
Another title followed in September, again on clay, but at the Madrid Masters Massu proved he was equally dangerous on hardcourts.
The Chilean stunned Andy Roddick in the third round on his magnificent run to the final - where he was edged out in three sets by Juan Carlos Ferrero.
The challenge for Massu now is to hang on to his place in the top 20.
A consistent hitter from the back of the court, the 24-year-old has an unusual service game which is surprisingly effective.