Justin Timberlake Did Call Troubled Britney Spears

There was no heartfelt letter.

But Justin Timberlake was so concerned about his ex, Britney Spears, who entered rehab in February, that he did reach out to her, he revealed.

"I called her because I worried about her," Justin Timberlake said recently at a press day for his new movie Shrek The Third.

But Britney Spears, who checked out of Malibu's Promises treatment center in March after nearly a month, is on the right track, Timberlake said.

"She's a great woman. I'm really rooting for her," he said. "[It] seems like she's getting everything under control now."

Timberlake, who just split with Cameron Diaz (his costar in Shrek, who also attended the press day), said being single has its ups and downs.

"The advantages are that you don't get in as many arguments, and the disadvantage is that you're talking to yourself," he said.

But he isn't exactly lonely. Timberlake spent time with Jessica Biel at a barbecue party at his L.A. house last week.

Things between the pair got "hot and heavy," says a source in the singer's circle.

This isn't the first time Timberlake and Biel have been spotted together: In January they went snowboarding with a group of friends in Park City, Utah, and hung out backstage at one of Timberlake's concerts in San Diego.

And at Prince's Golden Globes party that month, Timberlake and Diaz had a spat after Diaz saw Timberlake chatting with Jessica Biel.

As for Biel, when it comes to Timberlake, a source tells People Magazine that the hot actress is "crazy about him."

Who isn't?