Ainsworth was signed as a replacement for John Bostock, who returned to Tottenham at the end of his loan spell last week.
The Bees should otherwise be unchanged from the side which drew 1-1 with Southampton on Tuesday night.
Boss Andy Scott once again has a virtually full-strength squad to choose from with goalkeeper Nikki Bull the only absentee.
Bull is still recovering from the shoulder operation he underwent in October so Arsenal loanee Wojciech Szczesny keeps his place in goal.
Source: Team Talk
Source: Team Talk