The Jambos are seeking their first victory since manager John McGlynn parted company with the club last week, with first-team coach Gary Locke being placed in interim charge of team affairs.
The Edinburgh outfit will be looking for a positive result following the weekend defeat to Motherwell, with players also keen to stake a claim ahead of the Scottish Communities League Cup final against St Mirren later this month.
But Saints - sitting fifth in the table - are keen to pick up the wins that will secure their spot in the top half of the table before the league split. Lomas said: "Gary Locke is a very respected former player and coach. He's a great lad and I'm sure the lads will want to play for him.
"They've got a cup final coming up and maybe some of the more experienced boys have got a point to prove. There are various reasons why they'll want to do well but we can only focus on what we can do. We can only focus on our performance, our defending and our attacking."
He added: "The league's so tight and I think that's been a positive this year that everybody can beat everybody. Everybody has to perform because everybody can beat anybody on the day. If you don't perform in the 90 minutes, you get beat. It's as simple as that."
Hearts said they had more than 50 applications and notes of interest in the job in the first 48 hours that followed McGlynn's departure. McGlynn left Tynecastle after Hearts slipped to second bottom of the SPL but Lomas had some sympathy for the former Jambos boss.
He said: "It's a classic case of giving somebody a remit - blood young players while cutting the budget. But, once there is a little bit of heat coming from the fans, the manager is the one who gets the bullet when really John McGlynn has done nothing wrong. He's fulfilled his remit and more."
Saints were held to a draw by bottom side Dundee in their last outing but Lomas has no complaints about their recent efforts.
He said: "A point away from home in the SPL isn't something you need to bounce back from. Yes, we were disappointed but there's nothing we can do about it. All we can do is focus on the next game but I don't think it's a case of bouncing back."