RIO DE JANEIRO (AP) Brazilian swimming reached new heights in December when it topped the gold-medal table at the short-course world championships in Qatar.
The South Americans are a growing power in the sport, and the results seemed to bode well for the host country at next year's Olympics in Rio de Janeiro.
The celebrations have been short-lived.
The Brazilian swimming confederation confirmed last week that that Joao Gomes Jr., a member of three winning relay teams in Doha, had tested positive for a banned diuretic at the championships. Diuretics can be used as a masking agent to hide the presence of other drugs.
Brazil could be stripped of the three relay golds, Gomes risks a ban, and the Olympic host nation is getting unwanted attention for doping.
''This championship was a very impressive achievement for the whole sport in the country,'' said Brazilian Alex Pussieldi, a former Olympic swim coach and now a commentator on Brazil's SporTV. ''What was the best moment has to be a big nightmare.''
The respected specialist swimming website SwimVortex said Brazilian swimmers and water polo players were responsible for 18 doping cases since Rio was awarded the Olympics in 2009. It compares Brazil's doping record in swimming to Russia and China.
''One of the striking things about the cases is that they are all in-competition, not a single out-of-competition positive,'' SwimVortex said.
A 13-year-old Brazilian was recently banned for four months by the Brazilian confederation for a doping violation.
Pussieldi said his research shows Brazilian athletes were involved in eight of 17 positive tests for diuretics recorded since 2001 by swimming's world-governing body FINA.
The Brazilian confederation says it tests rigorously, which explains the positive tests.
In an interview with The Associated Press, Pussieldi blamed some of the problem on what he called a ''culture of taking supplements'' in Brazil.
''Parents and coaches and swimmers and athletes in all sports in Brazil really have the strong belief they will not be able to achieve anything is they don't have the supplements,'' he said.
FINA executive director Cornel Marculescu said a hearing on Gomes' case will be held next month.
''We don't disclose anything before we make a decision,'' he told the AP.
If Gomes is found guilty, Brazil will lose three gold medals and Hungary would move to the top of the medal rankings.
Gomes is a reminder of the 2011 doping case of Brazil's most famous swimmer, Cesar Cielo, a three-time Olympic medalist, including a gold medal in the 50-meter freestyle in the 2008 Beijing Games.
Cielo tested positive for a diuretic in 2011 at a national meet. The Brazilian confederation had jurisdiction and issued a warning. FINA appealed for a stiffer punishment from the Switzerland-based Court of Arbitration for Sport.
CAS upheld the ruling, allowing Cielo to compete in the 2011 world championships in Shanghai, where he won two gold medals. After one race, losing Kenyan Jason Dunford gave a thumbs-down sign.
''I don't mind losing to people,'' Dunford said. ''I'm just a bit disgruntled with the system that two months after a positive test he's competing against us.''
Brazilian lawyer Marcelo Franklin handled Cielo's defense, and will defend Gomes before FINA in Switzerland.
''He (Gomes) wasn't expecting it,'' Franklin said in an interview with AP. ''He even cried. Now he's very anxious to try to demonstrate that he's innocent.''
Franklin said Gomes could receive up to a two-year ban, but is expecting less.
''I'm going for no penalty at all, or a reprimand or a very small penalty,'' Franklin said. ''I will try to keep the medals, of course. They'll be little a little hard to keep.''
Franklin called this a ''unique case'' since Gomes swam only in the heats of the relays, and in none of the finals.
''It will be a little bit hard for the rest of the team to lose all the results,'' Franklin said.
Brazilian swimmers won two medals at the 2012 London Olympics, and there is pressure to produce more in Rio where home athletes will get a boost.
Brazil won 17 medals overall in London, and officials have a goal of reaching 30 in Rio.
''Everybody should be thinking about getting good times and getting ready for Rio,'' Franklin said. ''And now everybody is talking about the doping case. It's not good for anyone in Brazil. ... All eyes are upon us right now.''
AP Sports Writer Andrew Dampf in Rome contributed this report.
Stephen Wade on Twitter: http://twitter.com/StephenWadeAP