Millwall have signed centre-back Caleb Taylor from West Bromwich Albion for an undisclosed fee.
The 22-year-old has signed a "long-term" contract at The Den.
The move follows Japhet Tanganga's departure to Sheffield United on Thursday.
Taylor made 36 League One appearances on back-to-back loans at Wycombe Wanderers last season, playing in both legs of the Chairboys' play-off semi-final defeat by Charlton Athletic.
"He was our number one target all summer with regards to a centre-back," Millwall director of football Steve Gallen told the club website.
"With Japhet's departure, we've had to speed this one up - he is 22 years old, good in the air and good on the ball.