lpaul

Do you have further photos of this bird, especially any showing the crown pattern better?

lpaul

The poorly defined wing bars and very limited amount of grey below the lateral crown stripes are not typical of Bianchi's Warbler and fit Plain-tailed Warbler S. sorror better.  However, unless you have a photo which also shows the extent of black on the forecrown it will be difficult to be sure.

Based on the photos, I don't think this can be identified as Bianchi's.