McSweeney, who's hoping to regain his place at the top of the national team's order after being discarded perhaps harshly after just three Tests against India in 2024, cashed in on extraordinary run-fest at Canterbury as he raced to 101no off just 85 balls for Northamptonshire against Kent.
Remarkably, McSweeney, fresh from leading South Australia to back-to-back Sheffield Shield titles, was the lowest-scoring of the Northants' batters, with all four smashing hundreds for the Darren Lehmann-coached side as they amassed 2-684.
Opener and captain Luke Procter finished with a monumental 261no after 8 hours and 48 minutes at the crease, opener Ricardo Vasconcelas made 127 and Calvin Harrison a career-best 153, before McSweeney, coming in at No.4, powered to his ton with his second six, prompting an immediate declaration.
In Kent's reply, another of Lehmann's recruits Harry Conway then shone, picking up two key wickets, including a beauty to bowl England opener Zak Crawley, as they struggled to 6-119.
With Marcus Harris having scored 125 for Lancashire against Derbyshire at Old Trafford the day before, a hat-trick of Aussie Test opener tons had been on the cards on Saturday, but Jake Weatherald fell four runs short of a maiden county century for Leicestershire at the Oval against Surrey.
Fresh from securing a national contract, the 31-year-old Tasmania batter Weatherald looks on pole to again be an Australia opener in next year's Ashes, and he's looked good so far in his England recce, with 83 on his debut knock last week and this aggressive 96 before Reece Topley got him nicking behind.
He put on 156 for the opening wicket with Rishi Patel, who went on to make 133no, taking Leicester to 3-350 in response to Surrey's 520, which featured 166 from Jamie Smith and 103 from his fellow England batter Ollie Pope.
For county champions Nottinghamshire, Fergus O'Neill continued his brilliant return to Trent Bridge. The Victorian bowling allrounder followed up his first-innings half-century with two more wickets to finish with 4-24 off 13 overs and help skittle Glamorgan for 113.
He then added a valuable 23no as Notts made 9-284, with Joe Clarke scoring 136, as they finished in a dominant position, 450 runs ahead.
But Gloucestershire's Australian skipper Cameron Bancroft had another miserable day at Bristol. Having invited Durham to bat on a toothless pitch, he had to watch young England hopeful Ben McKinney make 244 of their 5-605dec and then got dismissed for just two as his side limped to 8-168.
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