NEW YORK - Mariano Rivera is backing Andy Pettitte.

After completing his $45 million, three-year contract with the New York Yankees on Monday, Rivera said he was impressed with Pettitte for admitting that he used human growth hormone after his name was included in the Mitchell Report.

“The thing that I admire is that he came out and said he did it,” Rivera said on a conference call.

Rivera was surprised to hear Pettitte was included last week in the report with Roger Clemens and several others on the Yankees teams that won four World Series titles from 1996-2000.

Pettitte later said he used HGH while he was on the disabled during the 2002 season.

“It was definitely the wrong thing to do,” Rivera said.

The Yankees' career saves leader said he spoke with Pettitte after the report was released and understood why the left-hander chose to try HGH. Pettitte said he was trying to hurry his recovery from an elbow injury and help his team.

“I might have done the same thing. Who knows?” Rivera said.

But Rivera also said he had “no idea” any of his teammates were using performance-enhancing drugs and that he was too “naive” to know what HGH was.