ANSWER
ANSWER
Most of you hit on the key to this puzzle. Like I said, this was an easy one, but I've seen games and played in a few where my opponet didn't see his opportunity to win with just a single leader.
Here is the original answer I published: [anything in "[]" was added today]
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The key for the Germans is to have the 10-3 survive (broke or otherwise) in the building. Probably upstairs via rout or ambush withdrawal. The Russians must find a way to prevent this.
German Rally: try to rally the squad. Not likely but don't forget to try. A 4DR or less will do it.
German Prep Fire: Here is where the decision making starts. The 10-3 is not going to fear the 4-4-7s to much, a 4+3 isn't much of a shot, and even if the 10-3 has to take a 1 or NMC he is likely to pass them. The only concern is the tank. Right now the tank needs a 6 or less to hit the 10-3 in the building, which will result in a 12 even shot. Again barring a CH (the tank needs to roll snake eyes followed by a subsequent dr of 3 or less) the leader should be able to pass any MCs.
So does the leader try for a PF or does he wait to move out of harms way? He'll need a dr of 2 or less to get a PF. I'd wait and do nothing in the Prep Fire phase.
German Movement Phase: I would move the leader to X1 via bypass, on the X1, W2, X2 vertex of course. This would make the tank turn his TCA giving him an even less chance to hit in the Russian Defensive Fire Phase. And the leader could still try for a PF in the Advancing Fire Phase if you want. The other option is to give the Russians no shots at all and move the leader to W2. The only problem with this is that he will be CX when he advances back into the building. Someone suggested that the leader could move into crest status in this hex, but I'm not sure what benefit there is in doing that because he would still be CX advancing back into the building (1MF to move off crest, 1MF to move over the wall, and 2MF to enter the building).
Russian Defensive Fire: The only question here is what hex the tank should acquire if the leader is not in the building. It doesn't really matter as long as the tank changes his TCA to face W2. This way all guns (mg and main) could be brought to bear on each building hex.
German Advance Phase: Advance the leader back to X1 or X2, which ever one is not acquired by the tank. Do Not Advance the leader upstairs if he is still in the building!
Russian turn:
Russian Rally Phase: Nope.
Russian Prep Fire Phase: The squads will have to move so they obviously won't fire. However the Russian player has to decide what to do with the tank. He could fire the MG's and Main Gun now and lose any opportunity to move the tank into the building hex with the 10-3, which would prevent the 10-3 from voluntarily routing upstairs, but does give the leader a better chance at ambush. 12 fire power MG attack plus at least two shots with the main Gun if it doesn't break on the first shot. No reason not to Intensive Fire at this point. However, even if the 10-3 breaks from the tank shots, it isn't over yet because the leader will just rout upstairs and deny the Russians sole occupation of the building. Therefor if the tank fires, the only good result would be a dead 10-3; not likely. Moving the tank is an option that needs to be considered and in fact the best solution in this case, so for this argument we will move the tank.
Russian Movement: First off the squads. One of them must move into the empty building hex. Since it is a rowhouse, the Russians must at least enter every hex of it in order to gain control. The good news is that they can do this without going CX. The second squad could move CX and try an infantry overrun vs. The 10-3. Not a guaranteed thing as he will need to pass NTC with a 3 or less (+3 building TEM and +1 CX)! Or should the last squad forget the CX and just move adjacent where he could move into the hex for CC? If you don't think a 4-1 odds in CC is good enough then you better not CX the second squad.
Now the tank will move into the building hex with the 10-3. The only question is what does he do, move into the building or in bypass. Both options will keep the 10-3 from routing upstairs. If the tank moves into the building he will risk crashing through the cellar, and if he is in bypass the 10-3 can try a PF TH attempt with an 8 or less if the leader has one and eats the Backblast. The other problem with bypass is the leader would qualify for ambush and could thus withdraw upstairs denying the Russians a chance to kill him in CC (there is a unofficial Q& A that is confusing in this matter, but I remember talking to ‘Mac' and a few others back at a past ASLOK and ‘Mac said' it was legal for the squad to withdraw upstairs before any Ambush drs are made because he qualifies for Ambush). Even if the tank moves into the building and survives the bog/cellar DR it would give the leader a +2 Ambush drm and if the leader ambushes the units in his hex once again he withdraws upstairs.
[Ok, we all know that MMP changed the rule to disallow Ambush Withdrawal in this situation.]
Rout Phase: If the Russian tank Prep Fired instead of moved and the Russian squad didn't succeed with the infantry overrun then the leader should break and rout upstairs. This would seal the German victory because the Russians don't have sole occupation of the building.
Russian Advance Phase: Simple, advance the Russian squads into the leaders hex if the tank is in there or if the German player didn't rout upstairs.
Close Combat Phase: At this point a lot depends on the Ambush dr. If the German leader wins it (if the tank is in bypass, it is easier) then he should withdraw upstairs and the game is over, if not then he needs to cross his fingers bigtime!