Speaking to the Western Mail Lennie said.
"It's a hard week and we don't get much time off, but we have to put a positive slant on it. It may be three games in six days, but I still expect to win them all and I expect the players to think the same way."
City will use their big squad to get through these games. Daniel Gabbidon, who is struggling, and Robert Earnshaw will face late fitness tests ahead of the league game on Sunday. Lennie continued.
"There is absolutely no way I will play Danny unless he is 100 per cent fit. It would make no sense at all to include him if there was any possibility of extension to the damage that would put him out for a number of weeks. His chances are odds against, but if Danny doesn't make it, we have good cover in either James Collins - who is OK after playing for the Wales Under-21s, or Chris Barker."
City are likely to line up. Alexander, Weston, Prior, Collins, Croft, Maxwell, Boland, Kavanagh, Legg, Thorne, Earnshaw. Subs from Margetson, Barker, Bonner, Bowen, Hamilton, Leo FW, Campbell.
City have just 48 hours to prepare for the visit of Tranmere after the final whistle goes tomorrow. The league of course is the most important thing this season but no fan wants to see their team lose and with the prospect of another Leeds Utd in round 3 of the cup there will be high hopes of despatching Tranmere at the second attempt.
Lennie said of the cup
"I'd rather be in a cup replay than out of the competition altogether so we will just get on with it. It's the reason why we have got a big squad. And it's why I rotated for the LDV Vans Trophy and FA Cup matches. We may need 18 or 19 players over the next six days. All of a sudden, someone who a few weeks ago didn't play much might be in the league team. Players have to be ready. It's no good people saying to me that they haven't played first-team football for two months."
City are odds on favourites to beat Chesterfield. 6 home league wins in a row inc 7 goals without reply in the last two games. Chesterfield were humbled at home last week when Morcambe knocked them out of the cup at Saltergate.
The game kicks off at 3pm on Sunday and is live on Radio Wales (882mw). City need to win to go second in the table.