Espinoza yesterday sealed a 2½-year deal with the Latics after four years at MLS side Kansas City. And the versatile midfielder is set to go straight into the side for today's FA Cup third-round clash with League One promotion hopefuls Bournemouth at the DW Stadium.
Wigan boss Martinez said: "Usually players spend more time preparing for a debut and getting used to team-mates.
"But Roger is so desperate to play as soon as he can that we hope to see him on the pitch against Bournemouth.
"The Olympics in the summer gave a great example of just what he can do on the pitch - especially with his performances against Spain and Brazil.
"He'll bring something new to the group and we hope to have many happy memories of him playing for Wigan."