Oprah makes Lindsay Lohan cry

Lindsay Lohan wept as Oprah Winfrey complimented her on David Letterman's show last night.

The 'Mean Girls' star - whose post-rehab attempts to get her career back on track are being recorded in documentary series 'Lindsay' on Winfrey’s OWN network - initially planned to prank call her mentor, but Letterman quickly blew his own cover and had a serious chat about his famous guest instead.

Lohan asked the audience: "I think maybe I should just call her right now. Should we call Oprah?

"I think so. Do you have a phone? Have we got a phone?"

Retiring talk show host Letterman, 66, took the phone and in a feminine voice said: "Yes, can I speak to Oprah Winfrey please? Hi, this is, uh, Lindsay Lohan's secretary."

He quickly owned up to his real identity when Winfrey asked who was on the line, causing her to reply: "Very good, Dave! The David Letterman who's retiring?!"

Turning the conversation more serious, the talk show host asked: "How's our friend Lindsay doing?"

Winfrey then spoke of her pride in the 27-year-old actress’ attempts to turn her life around.

She answered: "I think she's doing OK ... What do you think? ... I think she's doing really OK. I think to have cameras following you around for every phase of your life and you're trying to pull your life together, I think that's a really difficult thing. We're really pleased that she's making some progress."

Lohan, who has been in rehab six times, wiped away tears.