Warwickshire 400 for 3 (Sibley 207*, Rhodes 109) trail Kent 585 for 7 dec (Bell-Drummond 166, Dickson 161) by 185 runs

Warwickshire's Dominic Sibley's found claims that he had become the first batsman to reach 1,000 first-class runs for the season put under scrutiny as Glamorgan's Marnus Labuschagne also laid claim to the honour.

But what was abundantly clear was that Sibley - like Labuschagne - underlined that he is an Ashes contender as Kent's bowlers continued their thankless toil on day three of this Specsavers County Championship run-fest in Canterbury.

Sibley's record includes runs in the pre-season opener to the county season between MCC and the Champion County which was traditionally staged at Lord's but which now takes place in the UAE.

In a phenomenal display of concentration and will power, Sibley, the 23-year-old former Surrey batsman, took his total crease occupation to almost nine hours in reaching an unbeaten 207 from 409 balls and 31 fours.

After his marathon innings a delighted Sibley said: "We've played on some tough wickets this year and I was thinking about this opportunity a lot last night, and I told myself that I really needed to make the most of this chance."

As for his chances of forcing his name into the hat for potential Ashes selection, Sibley added: "A lot of people are chatting about it and there's a bit of hype surrounding my name, but I just want to keep batting and scoring runs. It's really that simple. If I keep batting and stay in the grove then who knows? We'll see what happens."

The World Cup has quickened conversation around Jason Roy but England are also watching Sibley - and neither England opening berth is pinned down with the likes of Keaton Jennings and Rory Burns the current incumbents.

Sibley's stoical innings helped Warwickshire to close on a season's best 400 for 3 off 143 overs as the visitors responded to Kent's summer's-best total of 585 for 7 declared.

Against a fellow Division One county in distress, which has had to resort to several loan signings to keep body and soul together, Kent have somehow produced one of the flattest pitches of the season.

Sibley and his opening partner Will Rhodes took advantage of the most placid batting conditions of the season to post a record opening stand of 221 in first-class matches between Kent and Warwickshire.

Having resumed on 142 without loss, Kent introduced the off-spin of Ollie Rayner after an hour but Rhodes swept his fifth delivery for a boundary to take Warwickshire past 196 - their previous best championship opening stand against Kent recorded by Dominic Ostler and Roger Twose at Edgbaston in 1989.

Rhodes again swept Rayner for his 14th boundary to reach his first century of the summer from 218 balls, but, only nine runs later, the left-hander chased a wide, full delivery from Grant Stewart to be caught behind for 109.

After lunch, Rob Yates succumbed to the second new ball when he nibbled outside off against Darren Stevens to be caught at slip as Kent's attack, which had hitherto banked maximum bowling points in every game, missed out completely.

Sibley, who became marooned in the 90s for 48 minutes, finally reached three-figures after tea with a clip to the mid-wicket ropes. The 10th century of his first-class career came off 241 balls and included 16 fours.

Kent made their next breakthrough when Sam Hain (40) aimed to glance against Harry Podmore only to be caught off a fine edge by Ollie Robinson, the in-form Kent keeper, diving way to his left.

Sibley ploughed on however, moving past his previous best score for Warwickshire of 144 not out scored against Sussex at Hove last season. He then went onto the back-foot to pull a Podmore bumper for four to reach 175 for his 1,000th first-class run of the season.

The landmark boundary also took him past Nick Knight's 174 scored against Kent at Canterbury in 1995, Warwickshire's highest individual score in matches between the two counties.

Sibley's record-breaking continued when, just before stumps, he reached the third double century of his career and his first for Warwickshire from 406 balls and with 30 fours as he and Adam Hose cut Kent's first-innings lead to 185 runs.

Though Kent could only manage to pick up one wicket in each of the three sessions, they will take some solace in restricting the Bears to only three batting bonus points as the dogfight to avoid championship relegation continues.

However, a final day of leather-chasing awaits Heino Kuhn's side on Wednesday, when Sibley will have one eye on surpassing his career-best 242, scored for his native Surrey against Yorkshire at The Kia Oval in 2013.