His grades were the lowest in the class.
This team is stuck at the bottom of the league.
最上 means 'highest/best', the direct opposite of 最下's 'lowest/worst'.
bottom layer; lowest stratum · lowest social class; bottom of society
bottom step; bottom stair; last line; last column; bottom row
lowest part; bottom
bottom floor; lowest floor
Compound of 最 (most) and 下 (below, bottom). The reading さいか is the on'yomi for both characters.