OAKLAND — If you are a member of the Raiders fan tribe that has waited patiently for top draft pick Amari Cooper to show some extended wide receiver synchronicity with quarterback Derek Carr … well, don’t get excited.

All right, get excited.

Because hints were there. Happy hints. In the first half of Sunday night’s 30-23 exhibition loss to Arizona — which the Raiders led by 12 points at halftime — there were four more successful connections between Cooper and Carr.

Oh, there were some missed connections, too. But the ones that worked gave us enough of a look at the possibilities. Four catches, 62 yards in two quarters of football, the best Carr-to-Cooper performance of the preseason to date. So it is easy to imagine what we could witness in the regular season if the two men continue to grow their relationship inside the secret Del Rio Chemistry Lab that has been constructed as part of the fancy new Raiders renovation project at their Alameda practice facility.

“Certainly, you’re seeing glimpses of a very bright future,” said head coach Jack Del Rio, proprietor of the aforementioned lab, when asked about the Carr-to-Cooper operation.

“We’re taking good steps,” said Carr. “We’re getting a lot of targets his way and a lot of balls his way this preseason. … But there are still some things we have to clean up.”

Yes. Early in the game, there was at least one obvious timing flaw that resulted in an incompletion. But in the second quarter, the chemistry cooked. It especially boiled on a beautifully timed play with Cooper running a 15-yard downfield comeback hitch while being covered by Pro Bowl cornerback Patrick Peterson.

Just as Cooper planted his feet and pivoted around, the ball was right there, released by Carr before Cooper even stopped and turned. He spun again after the catch, escaped Peterson and turned the play into a 36-yard catch-and-run to the Arizona 21-yard line.

“It was just a play that we’ve repped a lot in practice,” Cooper said, downplaying the moment. “It was just one play. I think it was a big play to help us get in great field position. But I still think we should have finished it off with a touchdown.”

That was indeed the preferred result. And to be honest, Carr didn’t have his best night. But points can be fretted over in September. In August, having a rookie who takes charge as a game’s leading receiver is not to be discounted. And thanks to the die-hard Raiders fans who filled up maybe half the seats at O.co Coliseum on a warm summer evening, we can tell you exactly what noise the Carr-Cooper chemistry formula did make and will make. Because each time they linked up, here is what the crowd yelled:

“Coooooooooooooop.”

The Raiders’ choice to draft Cooper was not influenced at all by the opportunity for fans to make the distinctive “ooooooooooo” sound whenever he catches passes. But it’s now officially a thing at O.co.

The sound came out once more on the very next play after the 36-yard connection, when Carr hit Cooper for a 13-yard gain — though as he mentioned, the drive ended in a field goal. And it happened again later in the second quarter, they combined for a 9-yard gain.

Of course, we must issue the appropriate warning. Keep in mind that this was not regular season “Coooooooop-ing.” This was just preseason “Coooooooop-ing.” Future results not guaranteed. And it would be a good idea for the two to complete a touchdown pass together eventually.

It can’t be stressed enough what Cooper can do for the Raiders’ offense. If he becomes a threat, Michael Crabtree (one catch for 6 yards Sunday) will find it easier to thrive at the other wideout position. The tight ends should find more space. As should the running backs.

That’s why those “glimpses of a bright future” were especially hopeful glimpses. The sight of those four Cooper catches were practically enough to override the ugliness of the final pass Carr threw for the night, an ugly 81-yard interception return by a rookie cornerback named Cariel Brooks on the first series of the third quarter.

That pick might also be the last pass Carr throws in the exhibition season because NFL quarterbacks frequently sit out the entire fourth preseason game. In the Raiders’ case, that will be Thursday in Seattle. If Del Rio follows the tradition, Carr should have two weeks to forget about the interception and two weeks to dwell on the more positive stuff from Sunday.

Carr and Cooper will likely conduct their remaining preseason experiments on the practice field rather than in Seattle. But after Sunday night, for those fervent chemistry scholars in the Black Hole, opening day against Cincinnati on Sept. 13 can’t arrive soon enough.

Contact Mark Purdy at mpurdy@mercurynews.com.