Pascal Wehrlein says he couldn't avoid crashing into Jenson Button on the opening lap of Sunday's Belgian Grand Prix.

The incident happened on the approach to Les Combes, when the Manor struck the back of Button's McLaren-Honda, forcing both into retirement.

Speaking later, Wehrlein added he was "unhappy" about the incident, but felt he had just been "unlucky".

"Yes, I was really unlucky. In Turn 5 the two drivers in front of me were fighting for position, braking late, missing the line, so I tried to overtake them into Turn 6 on the outside," he recalled. "Then, both came back on the line and when I saw that I wanted to brake and move to the inside but I couldn't avoid the crash.

"I'm really unhappy about it but that is what can happen on the first lap when you're starting in the midfield; that part I can't complain about and that's where I want us to be starting next time in Monza."

"I think P9 in Q1 was a really good measure of how strong we were here this weekend. That's the bit I'll take forward into Monza and work to maintain," he added.

"Of course, I'm sad for the team because of what could have been today in the race, especially with all the incidents that created some opportunities. But, we'll come back fighting next weekend.

"Not long to wait!"

Meanwhile, Button was philosophical, but also felt it was a missed opportunity.

"I got a really got start and actually managed to pass one Williams, a Red Bull as well and got alongside a Force India. Then all hell broke loose in Turn One, I was on the outside, so I had to run off the circuit to avoid the incidents, following [Nico] Hulkenberg, came back on, having lost a lot of places and then someone punted me on the back in Turn Five and caused a lot of damage to the rear of my car," he noted.

"I don't who it was or how it happened, but it doesn't really matter. I was just behind [Kevin] Magnussen but I don't know who was behind me. The hit launched the rear of my car into the air and caused quite a lot of damage to the back.

"I could have got really good points as after the incidents the guy that started behind me was running in fourth place... It happens, I've been around long enough to know that, so it was an early bath."