branching point

I find unbalanced endgames always full of surprises : how should Black proceed after 21...c3+ 22.Rxa6 ?

To me,  Rxa6 then Bb2 seems good?

Is there some trick I'm missing somewhere?

Rxa6?

Actually, would rather play 2... Bb2. Then his knight is tied down, and after exchange of rooks, and taking his rook, I will try to get my rook to b2.

Yeah I thought that Bb2 then dismissed it, but it does look quite strong.

Bb2 allows Rxa2... I think 1-... Rxa6 looks good, because it forces 2- Nxa3 (2-Nxc3 falls to 2-... Bb2). Then 2-... Rxa3 and the black rooks should dominate the a and b files.

Although after 3-Bb3, I have trouble seeing what black should go for.

2...Rxa6 3.Nxa3 Rxa3 4.exd5 cxd5 5.Bb3 was the actual game continuation, which looks pretty strong for black, but white can create some problems.

2...Bb2!? looks like a neat improvement, but 3.Rxa8 Rxa8 4.exd5 Bxa1 5.dxc6 and Black doesn't have that many pawns left, so I don't know...

c3 was a large blunder, Bb2 there was the move, black being around -4.5 (Rxb2 c3).

Houdini plays 2...Rxa6 (2...Bb2 being half a pawn worse.) 3. Nxa3 Rxa3 4. exd5 cxd5 5. Kd3 (Bb3 was best up to depth 16) Rc8 6. Bb3, transposing into my line except black moves the king to d6 rather than e6. I guess it's not good to block the open files when you have the rooks.

With a change like that it's probably most important to choose the position you're more comfortable in.

yes Scott, the line you mention was the game continuation -

I wouldn't call 1...c3+ a "blunder" (I'd love to blunder like this in my games ), even if 1...Bb2! is clearly winning : this is just not a move that springs to mind, especially if you think 1...c3+ is an easy win (and many human players would think it is)

I agree with your conclusion that Black should choose what he feels more comfortable with, so the game continuation is a logical choice, and looks like an easy win, unless you're playing against a computer !

After 2...Bb2 another continuation could be 4...Ra6, but 2...Rxa6 looks stronger :)