David McGoldrick's first-half double set struggling Coventry on course for an unlikely win over Di Canio's promotion hopefuls, but two goals in three minutes from Gary Roberts and substitute James Collins - a boyhood Coventry fan - rescued the Robins.
Di Canio, whose bid to recruit a proven goal scorer is being hampered by a Football League transfer embargo, said: "We got the ball into the box 32 times and scored twice. We need a top striker if we are to stay near the top.
"We were on top in this game, but Tranmere are top of the league and their top scorer has seven goals.
"We have got injuries, but we sat down 16 months ago with a three-year plan and if we stay in the middle of the league that is one more year. I was happy to see my players fight back, but we had the ball in their box 12 times before they scored."
Di Canio also played down talk of him replacing sacked Owen Coyle as Bolton manager, adding: "I don't want to talk about Bolton. I am loyal to my chairman Jeremy Wray and all the people in the club."