The National Treasure actress was snapped sipping an orange juice and checking her phone messages while out and about in Los Angeles on Wednesday (5 March).
Diane was looking very dressed gown in a simple grey T-shirt and grey jogging bottoms, teamed with comfy trainers and a cute pink satchel.
It's certainly a different look from the show-stopping glamour she oozed at the Vanity Fair Oscars Party on Sunday, 2 March!
Diane attended the glitzy event with her long-time boyfriend, Fringe star Joshua Jackson, looking gorgeous in a revealing black lace gown.
The couple sparked engagement rumours earlier this year when Diane was seen with a ring on her engagement finger, although reps for both parties declined to comment at the time.
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All the red carpet fashion from the Oscars in our gallery below!
Copyright: Rex Features Startraks Photo