Kent v Australians, Tour match, Canterbury, 3rd day June 27, 2015

Mitchell Marsh edges ahead in Test battle after ton

Australians 507 for 8 dec and 322 for 4 (Marsh 101, Watson 81, Riley 3-114) lead Kent 280 (Key 87, Johnson 4-56) by 549 runs

Mitchell Marsh has done everything within his power to press for a spot in Australia's first Test XI, leaving Shane Watson to prove his fitness as a bowler next week or risk being dropped from the side. Marsh and Watson matched each other shot for shot and run for run up to a point on another sun-dappled afternoon in Canterbury, but it was the younger man who ultimately blasted clear to show how destructive he can be.

Having been 8 not out at tea, Marsh went to his hundred from a mere 93 balls, rattling five sixes into the stands at the St Lawrence Ground and leaving Watson well and truly in his wake. Having made his hundred he immediately retired, allowing Brad Haddin some time in the middle alongside the more circumspect Watson, who started rapidly but played within himself thereafter in search of the right batting rhythm. He was ultimately caught on the midwicket fence aiming a slog at the off-breaks of Adam Riley, another century eluding him.

Ordinarily this occupation would have meant that Watson, the incumbent, would be more or less assured of taking his place in the XI for the first Investec Test in Cardiff. Instead it is actually Marsh who has fewer selection questions to answer after bowling presentably during an outmatched Kent's doughty first innings of 280. It has emerged that Watson suffered from "a few sore points" after the West Indies tour and was not going to bowl competitively in Canterbury.

He was seen rolling his arm over gingerly off the shortest of runs in morning warm-ups, and team management expect him to be able to bowl again in the tourists' final warm-up match against Essex in Chelmsford. Watson will need to, for a Test batting average of 27 in recent times gives him precious little in the way of credits should he be unable to fulfil Darren Lehmann's requirement of a fifth bowling option - not since the 2013 India tour has Watson played without bowling in a Test match; he missed two Tests in South Africa in 2014 when he could not.

Lehmann and the selection chairman Rod Marsh would no doubt have been taken by Marsh's power and confidence, for it is the sort of freedom with which they have hoped Watson could play since his shuffle down from No. 3 to No. 6 in the order to accommodate Steven Smith at first drop. Neither Smith nor Shaun Marsh batted after their first innings hundreds, suggesting they too have done all they can by way of preparation.

Chris Rogers found himself opening with the captain Michael Clarke, an unlikely combination that reaped 91 runs for the first wicket. Having made 70 on the Isle of Wight and 84 in the first innings here, Rogers looked more fluent once more, though he dropped his guard to flick Riley to square leg and depart for 45.

Clarke's innings featured a few diverting strokes, and he seems far more assured than the flighty figure who batted in the West Indies. However his exit for 47 meant he was still without an innings of truly substantial duration since returning from hamstring surgery, and will likely need to play against Essex as a result. Even so, all of Australia's batsmen will leave Kent having spent at least some time at the crease, a welcome sign for what lies ahead of them.

Another man who will be better for this run is Ryan Harris, who showed noticeable improvement with each of his first-innings spells, culminating in a sharp contribution on the third morning that reaped the wickets of Sam Billings and Adam Ball. Rob Key had remarked that the more Harris bowled the better he would be, and that is certainly how it looked as he made the old ball move and fizz.

Mitchell Johnson maintained the verve of his display on the previous day, when he had felt his pace was back near to where it had been during his reign of terror in 2013-14. It is questionable whether Riley ever saw the ball that left his off stump flat on the turf, and other short deliveries had the Kent tail hopping about.

"I felt like I'd probably dropped a little bit of pace throughout the West Indies and probably through the IPL," Johnson had told Fox Sports. "It wasn't too much of a concern for me - I was really excited about getting over here and playing in these conditions because I know the ball swings here in overcast conditions. It was just nice to get out there and let a few rip."

Letting rip is exactly what Mitchell Marsh was to do later. It remains to be seen how much impact his hefty blows will have on the minds of the national selectors.

Daniel Brettig is an assistant editor at ESPNcricinfo. @danbrettig