Bǐsài zhōng tā zànshí diànhòu, dàn zuìzhōng nìzhuǎn qǔshèng.
She was temporarily last in the race but ultimately reversed course and won.
Tips
memory
殿 means 'palace hall' (the grandest place at the back of a complex) + 后 'rear/behind'. The 殿 was always at the farthest back — so 殿后 means to guard that backmost position.