Hartley damaged his stomach playing against London Irish and missed Saturday's Guinness Premiership final day defeat at Sale.
But the England hooker has recovered and is back in training ready for the clash with Saracens.
The bad news for Saint
s is that Irish powerhouse Roger Wilson has been ruled out with an ankle injury.
The No.8 also missed the trip to Edgeley Park after being carried off against Irish.
Wilson was still using crutches when sitting in the stands to watch the Wanderers win the Guinness A League on Monday night and it could well be the end of his season.
Mallinder said: "It doesn't look like Roger will be ready in time for Friday's game."
It means Mark Easter will replace Wilson at the back of the scrum as he did at Sale on Saturday.
And after another fine display from the Wanderers in beating Wasps 37-0 on Monday, Mallinder will have some selection posers, particularly on the wing where Sean Lamont looks back to his best.
Mallinder said: "A strong squad needs good first and second team players. The Wanderers were fantastic, and to nil a team is a fine achievement. We defended well down there and to continue with that rout shows how far we have come.
"We have said all along that if you play well for the Wanderers then you need to be looked at. Those players playing well need to be rewarded. Players can play games, Barry Stewart started on Saturday and was very keen to play on Monday, so they can play on Friday.
"Winning the A League just brings the squad together, they will be in today and we will have a good competitive session and it just pushes standards up."
