Matthews’ $2.5 million dollar move from Sydney FC to Portsmouth was only confirmed on Monday (AEDT), but Mousinho wasted no time the thrusting the 20-year-old centre-back into starting side for Wednesday morning’s clash against Millwall at Fratton Park.

And despite Portsmouth losing 1-0 to remain just one place above the relegation zone, Mousinho was happy with the display of Matthews, who was rushed into the starting side after the late withdrawal of Rob Atkinson.

“We had Rob in the starting line-up all morning, but because of an illness, Hayden came into the side,” Mousinho said.

“All things considered, I thought his overall performance was excellent. He looked really composed out there.”

Matthews was on the field for 78 minutes before being replaced by Irishman Conor Shaughnessy.

“I haven’t had really much of a training week, so my calves started to cramp up at the end,” Matthews told the BBC.

“I was obviously disappointed with the result but I’m very grateful to have made my debut,

“It was difficult circumstances (against) a tough team that play a very direct way of football, but all in all, pretty happy with my debut and my performance.

“For me it’s about coming in and making a difference, and I hope I can do that.”

Portsmouth’s other recent signing from the A-League, former Brisbane Roar striker Thomas Waddingham, came on as a substitute in the 79th minute, replacing Scottish midfielder Matt Ritchie.

Waddingham, 19, scored in his weekend debut for Portsmouth in a 5-1 loss to West Bromwich Albion.

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