A cross from Justin Morrow in the 95th minute was sent on by Alan Gordon to Lenhart, who headed it home for the late equalizer.
Lenhart's first goal in the 82nd minute also erased a San Jose deficit and allowed the Earthquakes (18-6-7) to pull three points ahead of Sporting Kansas City in the race for the Supporters Shield, indicative of the MLS' best record.
Gordon scored in the 24th minute for San Jose.
Blas Perez scored twice and Matt Hedges also tallied for Dallas (9-12-10), which remained one point behind Vancouver for the fifth and final Western Conference playoff spot.
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