Yakubu is expected to lead the line for Blackburn and arrives at the Lane with an impressive 16 goals to his name in the league, despite Rovers’ fight against relegation.
That total sees him fourth-equal in the Premier League goalscorer standings and as Ledley points out, the Nigerian's goals have given his team the chance to beat the drop.
"Yakubu has been brilliant for them," said Ledley.
"He’s given them a chance to stay up with the goals he’s scored, all important goals.
"He’s a tough player to play against, physically strong and a great finisher. We’ll have to keep an eye on him."
Sunday is a crucial game for both teams.
We're chasing a place in the top four while Blackburn find themselves three points from safety.
"At this stage of the season you face teams who are after points for different reasons," added Ledley.
"It’s what you expect. It’s another game that we have to try and get three points from. It will be tough, but every game in this league is tough."