take the field
Synonym discussion
Sense: idiom/1
All four describe getting into position to start a sports match, but they differ in register and scope. 'Take the field' is a fixed idiom with a ceremonial, team-focused tone — you would hear it in news headlines and commentary ('The Lions take the field for the second half'). 'Enter the pitch' is more literal and common in British English, but carries no special drama. 'Go out onto the field' is a plain-language paraphrase suitable for learners at lower levels. 'Line up' shifts attention to the formal pre-match formation (teams are called onto the pitch and they line up for the national anthem). For casual speech you might say 'The teams are on the pitch now' rather than using any of these phrases.
Etymology
This phrase originated in 16th-century military language, where armies would 'take the field' to begin a battle — taking the battlefield. By the mid-1800s it had been adopted into the language of team sports, preserving the sense of moving onto a defined space to start a structured contest. The underlying metaphor (sport as war) is less active today, but the idiom retains its formal, occasion-marking tone.