Los Angeles - Rafael Nadal says he still has work to do on his game as he gets set to launch his claycourt season which the Spaniard hopes culminates with his ninth French Open title.
World number one Nadal lost in straight sets in the final of the Miami Masters tournament on Sunday to second seed Novak Djokovic.
Djokovic cruised to a 6-3, 6-3 win as he easily dismantled Nadal who has been hampered by a back injury which wrecked his Australian Open bid earlier this year.
Thirteen-time Grand Slam winner Nadal said despite the loss, which dropped him to 0-4 in Miami finals, he feels good about having made it to the final in Miami.
"It is great that I am in the top of the race arriving to the claycourt season," Nadal said. "But now we start on clay and I need to be 100 percent.
"I need to work hard and try to be in better shape for clay."
Miami is one of just three ATP Tour Masters 1000 events that Nadal has failed to win.
The Miami final started evenly until Djokovic broke Nadal in the first set to go up 3-2. He took the set when Nadal failed to return a serve.
Djokovic broke to open the second set then broke the Spaniard again in the final game of the match.
Nadal, who has two titles in 2014 in Doha and Rio de Janeiro, blasted two aces and won just 59 percent of his first serve points against Djokovic.
The left-handed Spaniard said he plans to remain in the US for a few days then fly back to Europe and head to Spain where he will train on the clay surface.
"To be able to play in the final here is a lot of points," Nadal said. "I had a few good matches so that gives me confidence to start a very important part of the season for me."
Asked on Sunday if his back is still bothering him Nadal said, "No. I am fine. Thank you very much."
Nadal's success on clay has earned him the nickname "King of Clay". By winning last year's French Open, Nadal became the first player to win a single Grand Slam tournament eight times.
Djokovic said Sunday he ranks victories over Nadal to be his most satisfying.
"He is definitely the biggest rivalry I have in my tennis career," said Djokovic.
The two met in last year's final of the Monte Carlo Masters which is the biggest early event of the clay swing. Djokovic won in straight sets 6-2, 7-6 (7/1).
After Monte-Carlo the players hit the clay the last few weeks of April and all of May in cities such as Barcelona; Oeiras, Portugal; Munich, Madrid and Rome.
Like Nadal, 17-time Grand Slam title winner Roger Federer is looking forward to feeling the clay under his feet.
The Swiss veteran said one of the best things about the clay swing is there is less distance to travel from tournament to tournament in Europe.
"I like the changes of continents and surfaces," said world number four Federer. "The next five, six months are going to be quite easy traveling-wise for us.
Federer lost to Japan's Kei Nishikori in the Miami quarter-finals and to Djokovic in the final at Indian Wells, California.
"The beginning of the year is tough when we go to Australia, and then the west coast and all of that; Dubai, as well," he said.
"The clay is something I have always actually enjoyed throughout my career. It's what I grew up playing on. It's where I played most of my tennis in my career."