Not only was Redknapp forced to watch a player who joined Birmingham in preference to Portsmouth, Chris Sutton, give a master class of modern centre-forward play. His team also suffered a crushing defeat by one of two sides below them at kick-off, while three defenders, along with the the Egypt-bound Benjani Mwaruwari, are now out of the FA Cup tie with Liverpool on Sunday.
How he would like to have paired Benjani, who has gone to represent Zimbabwe in the Africa Nations' Cup, with Sutton, who was making his home debut for Birmingham after Steve Bruce prised him from Celtic on a free transfer.
"Sutton would have been ideal and I'd love to have signed him," Redknapp said. "I spoke to his agent, but it was a bit beyond us. Everton were in for him as well. But there's nothing you can do. You accept it. I tried but it wasn't to be."
He described Sutton as a "proper centre-forward", praise indeed from one who cut his footballing teeth supplying crosses for Geoff Hurst at West Ham. "You can drop the ball in anywhere," he said. "He backs into defenders and holds it at the edge of the 18-yard box, and then he brings people into play. That's what we haven't got. Benjani showed some good signs, but he needs a partner."
There were other reasons for coveting the former Blackburn championship winner. "He has a positive effect on others," Redknapp said. "He's a leader on the pitch. Where do you find players like that? They're not around. They don't come up very often.
"There's every chance he could get Birmingham out of danger. But I think they've got a very strong squad anyway. Who'd have thought they would be in this position? I certainly didn't at the start of the season. I reckoned they would be a top-eight team."
Birmingham at last lived up to such billing as they scored five in the top flight for the first time since Manchester United were routed in 1978 and it was their first victory by five goals at this level in 47 years.
Jermaine Pennant and Emile Heskey oozed quality and confidence, and they should not be discounted from contention for England's World Cup finals squad. David Dunn and Mikael Forssell, appearing as substitutes, were no longer shadows of their pre-injury selves.
Curiously, neither main striker scored. But after Jiri Jarosik headed the opening goal, and Benjani wasted two opportunities to level for Portsmouth, Heskey's header and Sutton's dummy set up Pennant to double the lead. Matthew Upson put Birmingham out of reach with a free header from Pennant's corner ("scandalous", spat Redknapp) before Forssell, with a penalty he won himself, and Dunn, surging on to Sutton's deft back-heeled pass, completed the spree in stoppage time.
Sutton's impact was comparable to that of Christophe Dugarry when, like an exotic bird alighting on a nearby industrial estate, he landed at St Andrew's three years ago. Birmingham climbed out of trouble then and on this evidence have it in them to repeat the feat. The newcomer certainly looks capable of making the No 40 shirt his own.
As for Portsmouth, this should be a time of optimism after the injection of Russian capital. Yet instead of their squad taking on a fresh, improved look, it is now diminished by the departure of Benjani (preceded by Lomana LuaLua), injuries to his captain Dejan Stefanovic (cheekbone) and Noe Pamarot (hamstring) and the suspension of Andy Griffin.
Time, surely, for Redknapp to wheel and deal in his trademark fashion - before the transfer window closes and the relegation trapdoor opens.
Goals: Jarosik (5) 1-0; Pennant (37) 2-0; Upson (55) 3-0; Forssell pen (89) 4-0; Dunn (90) 5-0.
Birmingham City (4-4-2): Maik Taylor; Melchiot, Cunningham (Kilkenny, 81), Upson, Lazaridis; Pennant, Johnson, Izzet, Jarosik (Dunn, 74); Heskey (Forssell, 78), Sutton. Substitutes not used: Vaesen (gk), Gray.
Portsmouth (4-4-2): Ashdown; Pamarot (Karadas, 89), O'Brien, Stefanovic (Friske, 83), Griffin; Mendes, O'Neil, Davis, Matthew Taylor; Benjani, Pericard (Olisadebe, 53). Substitutes not used: Westerveld (gk), Hughes.
Referee: C Foy (Merseyside).
Booked: Birmingham Johnson; Portsmouth Griffin.
Man of the match: Sutton.
Attendance: 29,138.Reuse content