وَلَكِنَّهُ يُؤَخِّرُ غَسْلَ الرِّجْلَيْنِ إِنْ كَانَ يَقِفُ فِي مَحَلٍّ يَجْتَمِعُ فِيهِ الْمَاءُ
If the person is standing where used water collects around the feet, the feet are left until the end. If the water drains away and does not collect, they may be washed during the introductory Wudu.