Reese Witherspoon can't believe daughter Ava's almost 18 – and neither can we

/ Source: TODAY

It's been an unbelievably good year for Reese Witherspoon. Her Southern-style brand Draper James is doing banner business, she was just nominated for an Emmy for her role in the HBO hit show "Big Little Lies" and she recently returned from an adventure-packed wilderness vacation.

And now, she's about to mark an unbelievable milestone: In a few weeks her daughter, Ava Phillippe, will be all grown up.

"It’s so weird," the actress and mother of three told Entertainment Tonight. "I can’t believe (Ava's) 18!"

Of course, when you look at them together in the photo above, it's just as hard to believe Witherspoon turned 41 this year. They look more like sisters than mother and daughter.

"She’s great, and we did it together," the star said of their journey through the years. "I feel like we grew up together."

As for Ava, she thinks her look-alike mom is pretty great, too.

"You taught me to be kind, thoughtful, motivated, and strong, and I'm so lucky to have all your wisdom around me," she wrote in the caption of a sweet Mother's Day photo she shared in May.

The actress was just 23 years old when she and ex-husband Ryan Phillippe welcomed Ava to the world.

They also share a son, 13-year-old Deacon. Witherspoon has another son, 4-year-old Tennessee, with current husband, Jim Toth.