However, after the break Rangers ran riot to eventually triumph 4-2.
"The passing of the ball was half-decent by both sides but it's all about brilliance, which is what Mendes did," Strachan said.
"They had a bit of brilliance and we had two individual mistakes."
Strachan had no complaints about Dougie McDonald after the referee sent off Jan Vennegoor of Hesselink for kicking out at Kirk Broadfoot.
"I thought the referee had a good game," Strachan said.