Ian Bell and Kevin Pietersen answered their critics with a stand of 192 on day one of the first Test

By Oliver Brett BBC Sport at Lord's

Bell's 75 not out was made under enormous pressure, knowing he started the match as one of the favourites for the chop when Andrew Flintoff makes his imminent return.

Pietersen's fourth Test century at Lord's - only Graham Gooch and Michael Vaughan have more - was the latest episode in a remarkable international career.

And it all started, of course, with some stunning scores against the country of his birth in a one-day series in early 2005.

That these two right-handers should produce important contributions with England in some serious bother - having lost three wickets for three runs in 19 deliveries - made it an extra special day for a side determined to seize the initiative in this best-of-four series.

Bell has been accused of losing concentration after making good starts. Once settled, he has arguably the best technique of anyone in the side.

606: DEBATE Well Done KP great to see the form of 2005 returning to England's captain in waiting ...watch out for more from KP in this series! ROCKFMBUS

But too often he has cruised to 40, 50 or 60 before his internal computer has prematurely shut down.

That has been a deeply frustrating trend - someone as talented as him should have started this match with an average better than 41.79.

Pietersen suffers the opposite problem, in that he is such a hyperactive - though not particularly fruitful starter - that he can give his wicket away before giving himself a chance to play himself in.

When Bell came out to the crease at number five, Pietersen had not yet got off the mark, and it was the smaller man from Warwickshire who was the faster scorer initially.

There were some typically compact cover-drives for four, admittedly a couple of risky shots as well, but Bell's counter-punch worked as England reached tea on 163-3, Bell on 33 and Pietersen on 13.

After tea, the showman replaced the warm-up act, as Pietersen got stuck into the spin of Paul Harris.

For a man who has had to deal with Anil Kumble and Muttiah Muralitharan in the past 12 months, Harris's gentle stuff - on a first-day Lord's wicket - was unlikely to tax Pietersen any more than a junior net bowler would.

And so it proved.

Pietersen blasted one drive just wide of deepish mid-on for four - a slightly precarious shot. Next ball, he skipped down the track and did what he should have done the first time, hitting it high and handsome over the rope for six.

The sweep shot came out too, but not the 'switch-hit' from Chester-le-Street - this was a more serious innings altogether.

Eventually, Graeme Smith had no option but to send his fielders to the boundary ropes, and Pietersen, and also Bell, picked up the easy ones and twos on offer.

There were still one or two big shots from KP though, with Morne Morkel and Dale Steyn punished when they dropped short.

Pietersen was given a standing ovation by the Lord's crowd

And the shot through the covers off the back foot to reach three figures was special.

Afterwards, the applause continued for much longer than expected, as though the crowd were asking for an encore. But they will have to wait until Friday for that.

Pietersen said afterwards: "That was on a par with the 2005 Ashes, walking off with the 158 [on the final day of the series].

"I said earlier I would love to have that feeling again and the way the spectators here at Lord's supported me - it was exactly the feeling I had I in 2005.

"Right now, I feel as English as everyone else. The crowd just kept going [when he reached his century].

"I had to pull away again and say thank you, that just makes me feel so so loved now. I can't thank everyone enough for their appreciation and support."

The early part of Pietersen's innings had featured a madcap single to mid-on and a nasty blow from a Dale Steyn bouncer.

But the blow on the helmet only served to "wake him up", he said. And in between his shots, he was able to watch Bell's own vital contribution.

Pietersen said of his batting partner: "The pressure he was under before will be gone because the way that guy played today was truly remarkable and so, so special.

"It was one of the best knocks I've seen Ian Bell play. His first scoring shot when he drove Morkel for four, I had to say 'Am I playing with Ian Bell here?'"

At the end of the day, in the best sunlight of the day, South Africa's fielders sat in a heap by the pavilion. The coaching staff tried to encourage them to 'warm down', but there did not look to be too may takers.

It was England's day, and the tourists need to bounce back on Friday - a day Pietersen said would prove to be more important than the opening six-and-a-half hours of the series.