The central defender, on a season-long loan at Hillsborough from the Blues, is ineligible to play against his parent club at Stamford Bridge in their televised fourth-round meeting on Sunday due to cup rules.
But that will not stop Hector cheering on the Owls as they look to cause a shock against Premier League opposition.
He pointed to Bradford City’s win at Stamford Bridge at the same stage of the competition four years ago as evidence that Cup shocks are possible.
“It’s a free hit,” said Hector. “You never know in the Cup, anything can happen.
“Bradford went there and won, so anything can happen.
“For me, I will be behind Sheffield Wednesday. That’s the club I am working at.
“If they get through then I get an opportunity to play again in the fifth round. I will be supporting the lads.
“Chelsea have some fantastic players. Hopefully, they have a bad day and we have a good day.
“We have good players up top, it’s just about taking those chances when they come.”
In 2015 Bradford emerged 4-2 winners at Chelsea. The then Premier League leaders were 2-0 ahead after goals from Gary Cahill and Ramires.
But goals from Jon Stead, Filipe Morais, Andy Halliday and Mark Yeates completed a shock win for the League One side.
Wednesday will be cheered on by 6,000 travelling fans at Stamford Bridge for a 6pm kick-off. “The support here is unbelievable,” said Hector. “My family sometimes go on the train with them, and I know how the fans are, home and away.
“They will be travelling down in numbers, so it would be nice to get a result for them.”
The Owls are hoping Fernando Forestieri – out since December 1 through injury – could be involved on Sunday if he comes through training unscathed.
Former England, Chelsea and Liverpool defender Glen Johnson has retired.
Johnson was the first signing of Roman Abramovich’s reign as Chelsea owner when he joined from West Ham as an 18-year-old for £6m in June 2003.
Johnson, 34, made 54 England appearances and spent four seasons with Chelsea, winning the title with them in 2004-05.
He won the FA Cup with Portsmouth in 2008, moved to Liverpool for £18m in 2009, and had three seasons at Stoke City.