One poor result can kill a manager's career stone dead and Bobby Petta wants Lennon's to live on Bobby Petta does not want Neil Lennon to repeat Celtic's infamous loss to Inverness. That kind of result will kill any realistic chance of Lennon landing the manager's job on a permanent basis. The Hoops take on Ross County in tomorrow's Active Nation Scottish Cup semi-final and Petta knows all too well how disastrous a cup exit to lower league opposition can be. The Dutch winger was left sitting on the bench during the infamous 3-1 loss to Inverness at Parkhead back in February 2000. The result ultimately spelled the end of John Barnes' short-lived time as manager at Parkhead. Petta is desperate for Lennon to avoid a similar fate by steering the way safely to a place in the final and keep alive the Hoops most realistic chance of silverware this season.He said: "He knows the history, nobody forgets. He has to make sure they are motivated and that they don't slip up. That's the kind of thing you don't even want to think about. It's a new challenge against Ross County and there are no easy games these days so you can't take anything lightly. At Celtic, it doesn't matter who you play against - you always have to win and you are expected to win. They can't take any opposition lightly because this is the only prize they can win now. They've got to go in there and get the win and get their hands on the cup." Lennon knows winning the Scottish Cup would add some considerable weight behind his argument to stay in charge for next season. Petta went on: "He has to do it for himself but also for the players, for the club and for the fans. He's got to win this cup and at least finish the season on a high with some positives because people have been focusing on all the negatives. Neil has a new start and everything to play for. He has played two games, won two and now he will want to win the cup." Former team-mate Petta is not surprised to see Lennon take his first steps into management - but admits he is surprised that the Celtic hotseat is available to him so soon. He said: "I'm happy for him because it's not easy to step in and take over. He's had two wins from two games and has a few games left to play. He just has to finish on a high. He knows Celtic inside and out and he has been doing well. Whether he stays on or not at the end of the season, we will just have to see what happens between now and then. He communicates a lot, he reads the game very well and he is a winner. Even in training ground games, he wanted to win. That's what they need. Players like him, and the likes of Paul Lambert, you just know that you wouldn't be surprised if they became managers. I don't think anyone would have expected him to be the caretaker manager at Celtic but he is doing well. It's a good learning process for him as well, it's all good, positive stuff."