It threatened to be a long evening for Arsenal as two-time champions Wolfsburg were clinical with the opportunities that arose early on.
The competition’s top scorer Ewa Pajor was unmarked as she was slipped into the box for the opener, before Souza’s error teed up Sveindss Jonsdottir for Wolfsburg’s second.
Souza made up for her error just before half-time, heading in a corner, and Blackstenius found Arsenal’s crucial equaliser later in the second half.
But Eidevall remains cautious despite home advantage in the second leg as Wolfsburg have also enjoyed success in London.
In seven competitive trips to the city, Wolfsburg have never lost. That includes last year’s quarter-final draw at Arsenal which helped them progress.
“It’s amazing to see the resilience, the attitude and the work rate that the players have,” said Eidevall.
“But it’s only half-time. We’re happy with the performance and the result but it’s all up to be decided in London. We love playing in front of our supporters.
“I’ve heard we’ve sold 47,000 tickets. I think we have a very good chance of selling out the Emirates. Together we can make it possible to once again take Arsenal to a Champions League final. That’s our dream.”
Wolfsburg goalscorer Jonsdottir said they needed to be “calmer on the ball” to retain their two-goal advantage but she remains confident of reaching another final.
“We have another game so it doesn’t really matter. We’re going to go to London and win there,” she added.
Neither side play before next Monday’s second leg and Wolfsburg could be boosted by the return of German striker Alexandra Popp, while Arsenal hope to welcome back Australian forward Foord.