Since beating Matthew Stevens at the UK Championship in Bournemouth three weeks ago, Higgins has won one game in four attempts.
He was beaten by Alex Borg in the first round of the Rothmans Grand Prix in Malta and went under to John Parrott for the first time in their eight most recent meetings in the German Masters in Bingen.
"With hindsight I wish I had not gone to Malta," said the 23-year-old Scot. "I haven't been able to practise properly since the UK and I really need four or five hours every day."
Lee, who had suffered five previous defeats against against Higgins, said: "He can't play if you keep him in his seat. The problem in the past has been trying to keep him there, but I guess it was just a matter of time. Winning the Grand Prix gave me a lot of confidence, and I wouldn't be here if I didn't think I could win another title."
Ken Doherty gave the home crowd another victory to cheer when he defeated first round giant-killer Bradley Jones 5-2 to set up a quarter-final with the German Masters runner-up, Mark Williams. "I'm under more pressure because it's on my own patch, but it's a nice pressure to have," said Doherty, the world No 4.
"The crowd make you feel so good because they're cheering every shot. And the atmosphere will be even better if I manage to keep on winning. I beat Mark 6-2 in Malta recently, but that will count for little tomorrow afternoon. I'll certainly need to step up a few gears."
Williams compiled a break of 139, the highest of the event so far, in his 5-0 whitewash of Graeme Dott.Reuse content