Former England batsman Rob Key turned back the clock to defy Australia on the second day of the Ashes tour opener against Kent at the Spitfire Ground, St Lawrence.

Key, who last played a Test against Australia on the 2002-2003 tour Down Under, top-scored with 87 as Kent finished the day on 203-5 in reply to tourists 507-8 declared.

He hit 15 fours in his innings before being the fourth man out, caught by Shaun Marsh at mid-wicket off leg-spinner Fawad Ahmed (1-59).

Key shared an 81 -run partnership with opener Joe Denly (36) after the Kent innings had started disastrously.

Opener Daniel Bell-Drummond was beaten for pace by Mitchell Johnson and was leg before to the sixth ball of the innings without a run on the board for Kent.

Denly was next go, caught behind by wicket-keeper Brad Haddin off Peter Saddle (1-32).

Key and captain Sam Northeast started the recovery mission before Johnson struck again having Northeast caught by Haddin for 25 with the score on 140. Northeast hit six and three fours.

Key departed 12 runs later before Ben Harmison came and went for five, bowled by that man Johnson.

The left-arm quick finished with 3-42.

Sam Billings (24 not out) and Adam Ball (21 not out) saw Kent through to stumps.

Earlier in the day, young quick Matt Hunn finished with 5-99 off 27 overs as the tourists declared just after lunch after resuming the second day on 348-3 with Steve Smith on 71 and all-rounder Shane Watson on eight.

Smith, the No.1 ranked Test batsman in the world, went on to post his 19th first class hundred before he retired out on 111.

The one-time Sevenoaks Vine representative hit 13 fours and one six.

Watson (21) was next to depart, courtesy of a stunning catch at backward point by Denly off Hunn from a full bloodied cut shot.

Hunn ended Mitchell Marsh's breezy 30 by re-arranging his stumps before Haddin (35) and Johnson (32 not out) added 60 together.

Ball took a smart catch at slip off spinner Riley to send Haddin on his way before Ball took the final wicket to fall, that of Harris, caught behind by Billings for nine.

Ball finished with 1-87 off 16.4 overs while Riley ended with 1-96 off 26.

Play resumes at 11am on Saturday.