Igor Tudor's side conceded three times in the opening 15 minutes, two of the goals following calamitous errors by goalkeeper Antonin Kinsky who was immediately substituted.
A slip by Micky van de Ven also led to Atletico's second goal as Tottenham imploded before staging something of a comeback to eventually lose 5-2.
Solanke's goal at least gave Tottenham a glimmer of hope before next week's second leg in London, but he said it had been hard to recover from such a dreadful start.
"Obviously the first 20 minutes was difficult, very difficult circumstances which are one in a million," Solanke told Sky Sports on Thursday. "You never prepare for that. You prepare all week to go into a game, have a game plan and then stuff like that can happen, which is rare.
"That gave us a bit of mountain to climb, but I think overall, we try to take some positives. We know we've still got another game."
Kinsky's slip for the first goal and then a stray pass for the third saw him hauled off by Tudor, who has found himself under an intense spotlight after losing all four games since being named as interim manager after the sacking of Thomas Frank.
He will still be in charge for Sunday's away trip to Solanke's old club Liverpool when Tottenham will be desperate to avoid a seventh successive defeat in all competitions -- a run that has left them hovering just above the Premier League relegation zone.
"We've been so good in the Champions League this year but we know we haven't been anywhere near good enough in the league," Solanke said. "It's hard to put a finger on it, just changing one thing. I think we need to be better in every department. We're trying to stay positive and want to change it around.
"We need to be brave, we need to be strong and have full belief."
Tottenham are 16th in the Premier League table, one point above West Ham United and Nottingham Forest.
