Blink and you would have missed it but then you almost come to expect that from a former international who has myriad records on the CD honours board.
Needless to say, if statistics were the yardstick, Sinclair would have been impossible to drop for the past few years.
His 100 came off 161 balls, including 10 boundaries and two sixes not long after tea when CD were 214-2 after 67 overs.
"Playing with intent with Carl was the key," he said, adding the third-wicket partnership of 224 with Cachopa was fine but CD needed to build on it today.
Sinclair was unbeaten on 135 while rookie captain Kieran Noema-Barnett was 21 not out at No 5 as CD posted a handsome total of 301-3 when umpires Chris Gaffney and Evan Watkin lifted the bails for the day.
It was befitting that Sinclair and Cachopa eclipsed the third-wicket partnership record of CD Ingham and Mark Greatbatch in 1994-95 in Napier, as former Black Caps coach Greatbatch, who has been involved with the squad, was again conspicuous at the park and the CD changing room with coach Alan Hunt and assistant coach Lance Hamilton.
Explained Cachopa: "He's been a great asset to the side and has worked really hard with us and a lot of us batters have appreciated learning from a guy like that.
"It's great to have him in a CD set up," he said, lauding Hunt, Hamilton and fitness trainer Anthony Sharp, too.
"They've worked really hard in trying to get us right by giving us a certain amount of cricket and through that develop us as cricketers this pre-season," Cachopa said.
Sinclair said the wicket, after the visitors won the toss and had the Stags padding up, favoured the seam bowlers.
"The sun didn't come out much so the wicket wasn't that dry and the ball moved around all day and there was plenty of purchase for the bowlers, so it was quite tough to get myself in there," he said, emphasising patience was vital in getting his eye in.
Equally significant on the "sticky wicket" was the need to take advantage of errant deliveries, something the Firebirds were guilty of gifting at crucial times.
Sinclair said it was unfortunate Cachopa got out on the old ball, in what can best be described as a soft dismissal to spinner Luke Woodcock, caught at short fine leg to Mark Gillespie for 105 runs.
Eleven was a bad omen for CD openers Jeet Raval and Jamie How, who fell to new-ball seamers Dane Hutchinson and Gillespie in similar fashion - feathering the ball to wicketkeeper Luke Ronchi.
Young gun Cachopa, at No 3, who had carved up a patient 50 with No 4 Sinclair rolling into the double figures, brought up his ton with a defiant shot over Patel's head to straight drive but sweeper Gillespie prevented a boundary. His knock came from 205 balls, including 16 boundaries and a six in 278 minutes at the crease.
"Skippy [Sinclair] is a quality batsman and there was a stage that I was trying to give him the strike, really," the Heretaunga Building Society Cornwall allrounder said with a century on the heels of a Chapple Cup-winning one for Pay Excellence Hawke's Bay senior men's representative side the previous weekend.
"When he gets going it's good to watch. I've got the best seat on the other end of the house so ...
"Skippy's very good at manipulating bowlers so I learn a lot of him," Cachopa said, revealing Sinclair didn't say much but simply focused on batting.
Knowing he was close to bringing up his fourth first-class century, the Aucklander wanted to take a front-foot approach to nailing it.
"I tried to keep a positive intent and keep my feet moving as well," he said, adding the pair of them had deftly dealt with loose deliveries.
Cachopa was disappointed with his dismissal but shrugged it off.
"I suppose at the end of the day that's cricket so you take what you can get."
The battle-weary face of Wellington skipper Stephen Murdoch said it all outside the changing rooms.
"It was a long day in the end.
"We started off well, executing our plans, and they [bowlers] continued to do well throughout the day but it was a case of two batsmen getting in and doing well, and not giving us too many chances at the end of the day," Murdoch said.
He had no regrets about bowling first, feeling there was enough traction from the traditionally batting wicket earlier on.
"The ball was nibbling around a lot and, like I said, in the first session we thought we had the upper hand, or most of it."
Murdoch felt the wicket wouldn't break up or have a mind of its own in the next three days.
"Hopefully it's going to be a good track for us going down."
With the blessing of the weather gods, a bit of moisture overnight under the covers would enable Gillespie and Hutchinson to claim a couple more scalps with an almost new ball.
"We have got to come to the ground with the same attitude as today - come hard and pick the seven wickets as early as possible tomorrow," he said, adding their spinners had it tough but put in some good spells.
Sinclair described Patel and Woodcock as stop-gap bowlers but the batsmen had prevailed.
Last year's champions the Northern Districts Knights and Auckland Aces are not playing in the first round.