ISO setting advice needed

I have recently transitioned from coach to photographer/cheerleader for my daughter's indoor basketball games.  I could use some advice on how to take crisper pictures!  I find myself struggling to get the clarity I am looking for, and as a relatively new indoor sports photographer, could really use some advice!

I shoot with a Nikon D610 with a Nikon AF-S 24-70mm F2.8G lens.  Based on some online tutorials, I have been shooting in Manual Mode at 1/1000 shutter speed, F2.8, and what amounts to auto ISO at roughly 6400.

I find that my pictures a somewhat grainy, which I attribute to the high ISO, plus there are definitely times where I would prefer to be shooting a higher shutter speed, which will push my ISO even higher.

So... a few questions:

1. Is there a way to force the camera to shoot at a lower ISO, then fix it in Lightroom afterwards?
2. Is this a lens issue?  Should I be looking for something with a lower aperture than 2.8?  Most of the research I did indicated this should be a great lens for indoor sports.
3. Any tips would be so helpful!!

Example picture attached.

Thanks in advance!!

Dave

1. Is there a way to force the camera to shoot at a lower ISO, then fix it in Lightroom afterwards?
Because of low light, to get the shot, a photographer may underexpose and increase shutter speed and then in post expose correctly, this allows you to get the shot without blurr at the expense of noise. But it won't help you, you will be adding noise.

2. Is this a lens issue?  Should I be looking for something with a lower aperture than 2.8?  Most of the research I did indicated this should be a great lens for indoor sports.
If you were a Canon shooter I would say EF 135 F2.0.but I see no Nikon equivalent. I own a Sigma 135 F1.8  This lens would buy you another stop and a thrid. ISO would go from 6400 to 5000 shot wide open, but understand your focus better be right on because you will be at a narrower depth of field
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3. Any tips would be so helpful!!
You problem is light, you need more. Buy several Flashpoint 600 flashes. Point them at the wall are ceiling near the area you shoot, they are portable and run on battery. Pro photographers put their flashes in the ceiling pointing down.

But all of this seems moot. You got the shot, and you are concerned about a little noise. Go get Topaz Denoise AI, or if you have On1 photo raw 2022 editor, it has a AI denoise as well. Realize you posted a 2 inch high picture and I had to blow it up but with a higher resolution image On1 removed the noise from your picture.