Tā zài bǐsài zhōng yíng le dì yī lún, què kāishǐ zhānzhān zì xǐ.
He won the first round of the competition but started to become complacent.
Tips
memory
沾 means to get wet / to touch; 自喜 means pleased with oneself. The image is of someone so delighted they are dripping with self-satisfaction — complacent to the point of excess.