Yes, definitely Terek Sandpiper - as well as the short orange legs, notice that there is a pale trailing edge to the wing (but not as extensive as on Common Redshank).
There's also a Curlew Sandpiper on the photo, at the back on the right.
The Lesser Sand Plovers are mongolus/stegmanni (as most are at this time of year). This photo shows very well one of the useful features for separating from atrifrons-group: notice that there are grey feathers along the flanks of these birds, underneath the wing - this area is white on atrifrons, similar to Greater Sand Plover (this feature applies in breeding and non-breeding plumage).
