Thatcher set for Foxes return
The former Tottenham defender has been sidelined for the last month, after contracting pneumonia.
Thatcher last played for The Foxes against Manchester United in late September, but manager Micky Adams is set to return him to the fold after he helped the reserves beat Pompey's second string 1-0.
Foxes reserve team boss Peter Shirtliff said: "Ben Thatcher did much better tonight and his fitness is improving all the time.
"I think that he should now be in contention for the game on Sunday against Blackburn."
Adams will be buoyed by the return to fitness of Thatcher, as his defence looked decidedly shaky during the agonising 4-3 defeat by Wolves at the weekend.