However, the lead belonged to San Jose in the 21st minute when Chris Wondolowski took advantage of confusion in the Portland defence to fire home from close range.
Portland piled on the pressure leading up the half-time interval, but their frustration in front of goal would be a sign of things to come.
Portland pulled a goal back before the hour mark when Valeri picked out Alvas Powell, who fired in from a tight angle to reduce the deficit.
The hosts were level in the 74th minute thanks to Liam Ridgewell as the English defender found space inside the box to power home from Valeri's corner.
San Jose looked like they had stolen the victory with five minutes of normal time remaining when Wondolowski headed home his second of the match from a Shea Salinas free kick.
However, there was one final twist as Powell battled his way into the box before picking out Kalif Alhassan, and the substitute tapped home to hand Portland a point.