Boyd - who played for Hull in their FA Cup final loss to Arsenal last term - moved to Burnley on transfer deadline day this year.
The Scotland international is one of just five players to score in the Premier League for rock-bottom Burnley this season, who are still searching for their first win since returning to the top flight.
And wide man Elmohamady thinks stopping Boyd could be key on Saturday for a Hull side who have recorded just two league wins this term.
"Burnley is a game we will look to win, of course, but it will be very tough I'm sure," Elmohamady told the Hull Daily Mail.
"George was a very good lad here and a very good player too. We all know what he can do.
"I really enjoyed playing with him in the Championship and then in the Premier League.
"It has been a difficult season for them so far but we are concentrating on our game and getting a win."
Sean Dyche's Burnley were valiant for 70 minutes before losing 3-0 at Arsenal on Saturday and will welcome the chance to come up against a side in their half of the table.
While Burnley are yet to win, they have collected four draws from their 10 outings, indicating that their first triumph is perhaps around the corner - something that goalkeeper Tom Heaton believes.
"I don't think we're too far away and hopefully we can put it together and get that first win," Heaton told Burnley's official website.
"But it is important we keep learning from it and keep getting better. There is no lacking hunger and desire and we're not too far away."
To win against Hull, their defence will need to be on form, though, with only one side - 19th-placed QPR - having conceded more league goals than Burnley.
Burnley have dominated the recent meetings between the two sides, winning seven of the last eight - although just two of those were in the Premier League.
And Hull won the last time they met, Stephen Quinn's second-half strike giving the Yorkshire outfit a 1-0 win at Turf Moor in March 2013.
Hull goalkeepers Steve Harper (bicep) and Allan McGregor (shoulder) will miss out, as will defenders Michael Dawson (ankle) and Alex Bruce (hamstring), and forward Nikica Jelavic (knee).
The game could come too soon for Burnley's Steven Reid (groin), while Matt Taylor (calf) and Sam Vokes (knee) remain sidelined.
