Borussia Dortmund coach Niko Kovac admitted his side have "a long way to go" despite their recent uptick in form ahead of Tuesday's home Champions League clash with Lille.
Last season's Champions League runners-up are 10th in the Bundesliga and in danger of missing out on qualifying for Europe next season.
Kovac, brought in after Nuri Sahin was sacked in January, has steadied the ship.
Dortmund secured a second successive league win for the first time this season by beating St Pauli at the weekend, also just their second away victory of the Bundesliga campaign.
Former Bayern Munich, Eintracht Frankfurt and Monaco coach Kovac said Dortmund are turning things around.
"We have already become more stable, we work hard on that every day on the training ground or the meeting room," he told reporters on Monday ahead of the last-16 first leg.
"It's good but there's definitely room for improvement.
"We are still a long way from where we want to be. But I like the way the boys are going along with it."
Dortmund have only lost one of their past 16 games at their Westfalenstadion.
"Our stadium, it's a big castle. It's tough to play here – very tricky and very hard," said Kovac.
"I hope we can use the atmosphere to make an impression on Lille."
Lille have won Ligue 1 twice in the past 14 years but have never reached the Champions League quarterfinals.
They were the only French side to finish in the top eight in the new Champions League league phase, but come into Tuesday's match on the back of a 4-1 Ligue 1 thrashing at Paris Saint-Germain.