Pietersen (326no) provided the timeliest and most defiant of reminders to the England selectors, who are set to announce their squad on Thursday for the first Investec Test against New Zealand.
The long exiled record-breaker was not the only one with plenty to smile about by stumps as four others hit hundreds elsewhere, and several shared in notable stands.
Pietersen, as so often, took top billing nonetheless.
He batted all day against Leicestershire at The Oval in Division Two, having resumed on 35, and finished with 34 fours and 14 sixes from 373 balls.
After only fleeting support from his fellow frontline batsmen, he was unstoppable as he dominated successive century stands for the ninth and 10th wickets with Chris Tremlett and then Matt Dunn – who contributed just five.
Surrey closed on 528 for nine, for a first-innings lead of 236 so far.
Up in Division One, on day three of Warwickshire’s match at home to neighbours Worcestershire, Varun Chopra (107) was a familiar batting hero for the Bears – for whom Chris Wright (61no) and Boyd Rankin (56no) were an unlikelier pairing down the order.
The hosts were therefore able to declare on 321 for eight, and set a highly improbable target of 437, before Worcestershire closed on 88 for two.
Chopra, who had resumed on an overnight 72, hit 10 fours in his hundred – and then number 10 Rankin hit a maiden first-class half-century in an unbroken ninth-wicket stand of 114 with Wright.
All other fixtures, in both divisions, have reached only the half-way stage – and in the top flight, ball is dominating bat between Sussex and Middlesex at Hove.
The visiting seamers shared the spoils as Sussex were bowled out for 192 in reply to 269.
Then, before bad light brought an early close, new-ball pair Oliver Robinson (three for 38) and Steve Magoffin reduced the Londoners to 126 for six.
The bowlers were also in charge at Chester-le-Street, where Durham were all out for 163 – conceding a first-innings deficit of 82, after Nottinghamshire seamers VD Philander, Luke Wood and Brett Hutton all took three wickets apiece.
The visitors struggled second time round, though, principally to England Test hopeful Mark Wood – whose pace accounted for four for 39 before veteran captain Paul Collingwod finished things off with three for seven in 178 all out.
In pursuit of 261 to win, Durham were then 15 for one after six overs.
County champions Yorkshire were in control despite running into an in-form Michael Carberry at Headingley.
But – like Jack Leaning (82) before him, in the White Rose’s 370 all out – Hampshire’s former England opener fell short of his century, making 97 off 208 balls.
James Tomlinson (four for 86) and veteran Andre Adams (three for 68) had led the way with the ball for Hampshire, who still seemed set to concede a significant lead on 223 for eight at the close after Jack Brooks and Adil Rashid each took three wickets.
Down in Division Two Northamptonshire were indebted to their lower-order batting – specifically England one-day international call-up David Willey (103) and Josh Cobb (95) in a seventh-wicket stand of 163.
The visitors therefore recovered from 101 for six against Derbyshire at the Racecourse, Tom Taylor and Mark Footitt both taking three wickets, to reach 324 all out and a deficit of only 19.
Derbyshire then moved to 76 without loss in their second innings.
At Canterbury, William Bragg (104) helped Glamorgan stay just about in touch against Kent, after Michael Hogan had finished with five for 71 in the hosts’ 357 all out.
Number three Bragg kept the Kent seamers at bay to reach his fourth first-class hundred from 179 balls, having hit 12 fours.
Glamorgan could still muster only 281 as Matt Coles, Ivan Thomas and Darren Stevens all took three wickets.
Kent then reached one without loss in a solitary over.
Opener Paul Horton (134no) shared a third-wicket stand of 134 with Ashwell Prince, in Lancashire’s 276 for six at Old Trafford.
Horton hit 16 fours from 242 balls in all, after Lancashire seamers Peter Siddle and Kyle Jarvis had earlier shared seven wickets.
But the Red Rose still had work to do in reply to Gloucestershire’s 388 all out.