Complex sentence: In 2000, Häkkinen won 4 races but conceded the title to Schumacher with 2001 yielding two victories and the announcement of a sabbatical that later turned into retirement.
Split into simpler sentences: In 2000, Häkkinen won 4 races but conceded the title to Schumacher. This was followed by two more victories in 2001, and the announcement a sabbatical the same year that later turned into retirement.