02/11/2013 09:52 EST | Updated 04/13/2013 05:12 EDT

Rafael Nadal is back, but the old game isn't quite the same - at least not yet

VINA DEL MAR, Chile - After seven months away treating a torn and inflamed tendon in his left knee, Rafael Nadal left many questions unanswered in his comeback tournament.

Nadal lost both the singles and doubles finals in the space of a few hours on Sunday at the VTR Open in Chile. And Horacio Zeballos, whose three-set victory over Nadal in singles brought him the first title of his career, repeated what Nadal has been saying.

"Not playing has hurt him," Zeballos said. "Four or five tournaments back should get him back in form. I'd say this was the perfect time to play Rafa considering the confidence factor and everything."

In the final, Zeballos served better, hit more cross-court winners from sharp angles, and was quicker on clay than the Spaniard, the seven-time French Open champion who was introduced throughout the tournament as "The King of Clay."

Nadal said the loss was a reminder of what he already knew: returning to challenge the other three in tennis' top four — Novak Djokovic, Roger Federer and Andy Murray — will be slow and gritty.

"It was a week when we didn't know how the body would respond, the knee," Nadal said. "At least we have seen we can compete up to a certain level. It's true I have had good days and bad days that impact on my play. The tennis aspect isn't the most important thing. The most important was being out there again in front of fans. But I won't deny I wanted to win here."

Despite the positive spin, Nadal lost to a player he beat in straight sets three years ago in the French Open — 6-2, 6-2, 6-3. Nadal has won 50 tournaments on all surfaces, and Zeballos now has won one. Nadal has $50 million in tournament earnings, while the Argentine has a mere $1.3 million from tournaments.

Nadal moves this week to the Brazil Open in Sao Paulo, an event that provides another test on his road to the French Open. He competes again on clay later this month in Acapulco, Mexico.

The torn tendon in Nadal's left knee drew repeated questions. He said it's better some days than others, and there's still pain. He's avoided surgery, and he says he's been told by doctors the soreness may linger for a few more weeks — even a few months. He wore a white bandage on the knee whenever he played, racing down plenty of loose balls and showing no signs of protecting the knee or, for that matter, his right knee, which has also been injured.

"Every day improves and increases the confidence for me," he said. "Every day that the knee answers well is a lot of positive energy for me, and that's helping me a lot. The feeling day by day is better — the feeling on court. ... I still feel pain in the knee some days and that's something we hope and think will be improving week by week."

Nadal looks slimmer than before, and his powerful forehand appeared to be recovering faster than his serve and backhand.

The Spaniard was wildly popular in Chile, with newspapers tracking down some distance relatives in the country. He was asked repeatedly by local reporters if he would return — this was his first tournament in the South American country — and he said the diplomatic thing: he'd like to, but his schedule next year is tough to predict.

He also promised to talk up the event with players like Federer and Djokovic, which was his response when asked if other top stars might show up in this Pacific coastal resort.

Things have marched on since Nadal's been away — the London Olympics, Grand Slams in the United States and Australia, and Spain's shock ouster from the Davis Cup earlier this month by Canada. His ranking slipped to No. 5 and will fall farther after being out for seven months.

In the wake of the Lance Armstrong scandal, tennis — like all sports — is coming under closer examination for the possible use of performance-enhancing drugs. Armstrong, after denying he was cheating, admitted last month that he used banned substances in all seven of his Tour de France victories.

Inevitably, Nadal was asked about doping in two news conferences — by Chilean and non-Chilean reporters. He said he's open to more testing, but complained that some players are being tested more than others.

"Not everyone has to pay for some sinners," Nadal said.

He said he had passed six blood and urine tests since losing on June 28 at Wimbledon — his most recent tournament before playing in Chile. He said it should be made public who is being tested, and how frequently.

"If I go through a lot — or very few doping controls — people should know," he said. "Though I went for seven months without competing, I went through a lot of tests.

"I don't have to justify anything," he added. "This information should be open the public."

All top tennis players are subject to being tested without warning.

"The important thing is that those who are cheating, pay for their cheating," he added. "With Armstrong the image of sport has been damaged, especially in the case of cycling. The important thing is for sport to clean up its image, that the controls are made public."


Follow Stephen Wade at