Below the mark and Second string

Second string and below the mark are semantically related. In some cases you can replace phrase "Second string" with "Below the mark", this phrases are similar.

Second string noun - A squad of players that are available either individually or as a team to relieve or replace the players who started the game.

Below the mark and second string are semantically related. Sometimes you can use "Below the mark" instead an adjective phrase "Second string".