Tactics: White to play and... survive?

This week's Canadian Tactic comes from the 2014 PanAms, the North American University Championship, held on South Padre Island, Texas in December. In round 1, GM Anton Kovalyov had Black against an opponent he outrated by nearly 900 points. Instead of going for complications, Anton played his slow QID (3...b6, 4...c6, 5...d5) and slowly equalized. Late in the middlegame, possibly with White in time trouble, they reached the following position:

 

 

 

 and Black played 27...Ne4+.

 

White to play and...

 

 

 

 

 

The variations below are long and tricky, so rather than the usual Position with "Hints", here is a clickable version of the game:

 

() - ()    Round:  Result:

A report on the Pan-Ams, including the game: Duncan Shepherd (1725) - Anton Kovalyov (2619) (Pan American Intercollegiate-chT, South Padre Island), 2014.12.27 will appear in an upcoming issue of Chess Canada, the CFC's online newsletter.