Sandpiper (?) help needed

This bird was seen at Morro Bay CA last week. There were one or two of these guys in with lots of Long Billed Curlews and Marbled Godwits. It is quite a bit smaller than the Godwits. I think it is some kind of Sandpiper, but the yellow/green legs and lack of white fringe on the feathers has me stumped. OK, it doesn't take much in general to stump me! Apologies up front for posting two images, but they are small - about 92KB combined. Sorry, I don't have any shots with the wings open.

Alan, Take a look at Red Knot (they are brighter in spring!).

Thanks Declan. Knowing what to look for I found a photo that is a decent match in the Audubon iPad app, taken by none other than Arthur Morris.

Good on Declan. Yes, a Red Knot, in fact, a first winter bird. See the feathers of the lesser coverts, the ones with the dark shafts and the small white fringes? Those are retained juvenal feathers....