Northamptonshire 86 for 2 (Vasconcelos 37*, Zaib 22*) vs Nottinghamshire
Vasconcelos - having been dropped twice as he progressed to 37 not out - batted right through the morning session at Wantage Road to add exactly 50 for the third wicket with Zaib, who posted an unbeaten 22.
That stand enabled Northamptonshire to reach lunch at 86 for two, with Luke Fletcher and Dan Paterson taking a wicket apiece, but further progress proved impossible after a heavy downpour during the interval left the playing surface saturated.
Umpires Neil Pratt and Richard Illingworth abandoned play for the day shortly after 3pm.
Despite missing England pace duo Stuart Broad and Olly Stone from their bowling attack, Nottinghamshire skipper Steven Mullaney opted to insert the home side after winning the toss.
Emilio Gay, back at the top of the order after a knee injury had ruled him out of Northamptonshire's first four matches this season, displayed no signs of rust as he dispatched Fletcher to the fence three times.
However, Fletcher probed away to get his man, moving one away to find the edge into Joe Clarke's gloves and that dismissal, along with a consistent spell from first-change Paterson, stifled the scoring rate.
Paterson picked up the visitors' second wicket with a beautiful delivery that seared back a long way to crash into Sam Whiteman's off stump - and they should have had a third after squandering two opportunities to remove Vasconcelos.
Brett Hutton spilled a routine slip catch after the left-hander wafted outside off stump at Lyndon James and he was afforded a second life when Clarke failed to hold onto a leg glance off Paterson.
It took Vasconcelos 89 balls to register his first boundary, belting a rare stray delivery from Paterson through the covers, but the second and third quickly followed in Fletcher's next over as he and Zaib built a solid partnership.
There was another scare for Vasconcelos just before lunch, having second thoughts about a quick single as he stumbled halfway down the wicket, but regained his footing to scamper to safety at the non-striker's end while Matthew Montgomery's throw flew wide.