Middlesbrough are running on empty in the League but their cup was looking half full until a late intervention by Herita Ilunga earned West Ham a replay they just about deserved.
Boro, second-bottom in the Premier League, had led since the 22nd minute through the classy Stewart Downing and looked to be heading into the last eight for the fourth season in succession with a display that belied their recent troubles.
But West Ham's lively substitute Savio, a German youth international, sent in a free-kick conceded by Gary O'Neil in the 83rd minute for Congolese defender Ilunga to nod home his second goal of the season.
Goals have been in short supply for both teams, particularly Boro. On yesterday's evidence, there is still plenty to do in that department, with West Ham's array of foreign talents particularly wasteful.
Adam Johnson and Downing pulled shots wide from good positions before Downing made amends. A starter for England in Seville, the left-footed midfielder headed in from close range after O'Neil's cross had embarrassed Matthew Upson and James Collins.
West Ham had chances, too, in a bright first half. Mark Noble, twice, and Collins were denied by Brad Jones. Their representatives in Spain did not fare well, Carlton Cole limping off with an ankle injury, Upson out of sorts and Rob Green left exposed in goal.
The managers faced each other in the 2000 final, when Gianfranco Zola's Chelsea beat Gareth Southgate's Aston Villa at the old Wembley. Both fielded their strongest sides in what was also a re-run of the 2006 semi-final. Boro scented revenge for that loss and they could have gone further ahead had Green not got down to save smartly from Afonso Alves after an hour. Downing, too, was denied by an excellent one-handed save from Green.
Boro could have been out of sight. "We got ourselves in some good situations but that has been a feature of our play recently," Southgate said. "However we played some good football and were well worth the draw."
The Hammers were also asserting pressure, much of it frenzied, but their finishing was dreadful. Diego Tristan lost his footing when through on goal and David Di Michele missed after Collison and Ilunga had combined superbly.
Finally the equaliser came, though, Savio's set-piece eluding everyone bar Illunga, who stooped to head home at the far post. "We deserved the draw because we created so many chances," Zola said. "The body was there but sometimes the mind was not."
Referee: Peter Walton
Man of the match: Downing
Match rating: 7/10Reuse content