With his frustrating wrist injury finally behind him and the US Open looming large next month, the smile is back on Juan Martin Del Potro's face as he prepares for this week's ATP event in Los Angeles.

The towering Argentine played just three tournaments last year because of an injured right wrist but all that is largely forgotten and he is excited to be back in form with the US hardcourt season ahead of him.

"It has been a very long while (with) my wrist injury but now I'm OK," former US Open champion Del Potro said while preparing for his opening match at the Los Angeles International.

"I'm getting better with my tennis, with my mind and my problems are in the past. I am not thinking about my wrist, about different injuries that I had last year.

"Now I have everything to improve, starting with my ranking, with my game, with my body and with my physicality."

Del Potro has won two ATP titles this season - at Delray Beach and in Estoril - and has climbed from a lowly 484th in the rankings in early February to 19th this week.

"I just want to improve my game and be at the top as soon as I can," said the 22-year-old, who won the Los Angeles International in 2008 and his first Grand Slam title the following season at the US Open.

"I know it's a long road, a very tough road, but I still believe in my game. I am very confident with my level at this moment."

Del Potro, seeded second in Los Angeles, said: "I am lucky to be top 20 at this moment but it was really tough for me to come back, especially in the beginning of the season when I was in the Australian Open and I lost in the second round."