Panesar broke the back of the Pakistani top and middle order on the final day of the Old Trafford Test with a five-wicket haul and since then his list of admirers is getting longer every day.
''I think Monty can be a fantastic bowler. I fancy my chances against most spinners and I honestly think that he is up there,'' Pietersen told BBC Five Live.
''Not putting any pressure on him but from what I've seen so far I think Monty can be really, really good,'' he added.
Himself a good player of spin bowling, as was underlined in his Ashes duel with Shane Warne last year, Pietersen felt Panesar would go a long way.
Strangely, Panesar is yet to convince his coach and Fletcher harps the youngster needs to improve his batting and fielding before he can think of cementing his place in the side.
Fletcher, however, looks alone in his view and former England skipper Ian Botham, in his Daily Mirror column, wrote ''It's time to stop patronising Monty Panesar about the need to improve his batting or fielding and accept him for what he is the match-winning spinner we've craved for years.'' ''To think that England were even toying with the idea of leaving out Panesar at Old Trafford beggars belief, but now he has taken two five-wicket hauls in the last three Tests he should be undroppable,'' he said.
''His double act with Steve Harmison was one of the best pace-and-spin combinations I've seen for some time and it reminded me of the way Australia use Glenn McGrath and Shane Warne in tandem when they are going for the jugular,'' Botham said.
Former Australia wicket-keeper Rod Marsh also felt that England should take Panesar to Australia, considering their left-arm spinners have traditionally done well Down Under.
''They've got to bring him here (for the Ashes). He's become a bit of a cult figure in England. The crowds will love him here - one way or the other,'' Marsh said.
''I'm sure the Australian batsmen will go after him, but they'll do that against any spinner. He's got good flight. He hasn't got much variation, but he's got good drift. He puts a lot on the ball, he's got extremely long figures ... he's good,'' he said.