DD did something very similar at about 10 months.

I too was worried that she was up for so long in the afternoon after a sleep in the morning, but it didn't worry her. It was me who needed a break.

If she did get grouchy in the afternoon I'd take her for a walk in the pram. Sometimes she would have a little nap, but even if she didn't she had a rest.

Once the arvo sleep was definitely gone the morning sleep started getting later. That was through DD's choice, but you could also stretch it out if you like.