However, the manager, Arsène Wenger, provided an even greater surprise by stating that there was no need for him to buy in the January transfer window.
"It depends what there is on the market," said Wenger, who nevertheless admitted that he was finding this season "frustrating". "We don't need to buy for numbers. If super-quality comes up then, yes. We will try to have a look."
Henry, having recovered two weeks early from a groin injury, certainly falls into that category and Wenger hopes to bring the striker on for "30 or 40 minutes" against the Czech champions and then start him against Manchester City on Saturday.
"I feel we need a bit more weight, experience-wise, in the dressing-room," Wenger said of his decision to travel with Henry. Wenger lamented the recent loss of Sol Campbell and Gilberto Silva, saying that he had been deprived of "the spine of the team" which also makes the hiatus over Henry's stalled contract talks all the more wearing.
Until recently that spine would have included Patrick Vieira and Wenger also admitted that he had given some thought as to whether or not he had been wise to sell the midfielder. "I've thought about that but, you know, in the first seven games of last year we missed Patrick and now he's injured [at Juventus].But as long as you don't win games people say you make mistakes and you have to accept it. I don't feel it was a big mistake." His faith in Cesc Fabregas and Mathieu Flamini remains unshaken - they have done "extremely well" - and Wenger believes that his team simply needs "time to grow".
That is not something available right now with the scrutiny heightened by the dispiriting loss to West Bromwich Albion, which sealed their worst League start since 1994. Defiantly, Wenger intimated that with 17 shots on target to their opponents' four the result would have been very different with Henry. "He's out for 37 or 38 days and still our top goalscorer," Wenger said. During that time Arsenal have floundered.
"We don't say goodbye to the title because we will fight until the last second we have a mathematical chance," Wenger said. "But at the moment I have to accept that we are far from Chelsea." Indeed, it is not just the champions. "Before we come back we have to come back on the other group of teams and then come back at Chelsea."
There is more than that at stake. "We have our pride and have finished always in the top two," he said of his record as manager. Wenger bridled at suggestions that Tottenham were about to usurp his team as the power in north London, never mind the country. "We have eight games gone. They are doing very well but I don't even think about that."
Wenger said that he took heart from the fact that fewer games had been played at this stage of the season than was usual "and the championship will really be played after January". He added: "I'm very confident that we have the quality to come back to the top of the table but at the moment I look a bit lonely in that." Is this his greatest challenge? "When you speak of the title then it is a huge challenge now because Chelsea's far [ahead]."
It has led to a belief that, maybe, even after all their failures in Europe, the Champions' League may be Arsenal's best hope this season. But Wenger said: "I hate to put the chances of the team on a cup competition because the real quality is in the championship."
Arsenal are in a strong position to progress from Group B victory against a Sparta side in disarray, having sacked their coach and one of their best players, Karel Poborsky, and Wenger believes that his team will need just a point from their final three group matches if they win tonight.
Wenger hit back at claims by the former Arsenal goalkeeper Graham Stack that cliques are rife at Highbury, by insisting that squad morale was as strong as ever. Stack claimed that his former team-mate Ashley Cole had given him an insight into morale at Highbury, stating "the cliques aren't rumours, it's a fact". Wenger said: "It's a very unfair and unjustified comment by someone who hasn't been part of the first team squad at Arsenal for 24 months."
Arsenal (probable 4-4-2): Lehmann; Lauren, Toure, Senderos, Clichy; Fabregas, Flamini, Gilberto, Pires; Reyes, Van Persie.
Sparta Prague (probable 4-4-2): Blazek; Pospech, Petras, Petrous, Kadlec; Kisel, Hasek, Zelenka, Polacek; Slepicka, Matusovic.
Referee: W Stark (Germany).
The Lowdown on... Sparta Prague
* How do they beat you?
Sparta Prague, who have qualified for the Champions' League group stages for the past three seasons, have a reputation for being difficult opponents. The telling battle will be for the midfield. If Prague can dominate then Lukas Zelenka will create time and space to feed the top scorer Miroslav Slepicka. Tomas Sivok, the 22-year-old defender at the heart of the defence, will be relied upon to halt the runs of Jose Antonio Reyes.
* How do you beat them?
Prague conceded late goals against FC Thun and Ajax last month. They lie at the bottom of Group B, and have not won any of their past 10 Champions' League games. In the Czech League they have known better days, with nine points from 13 games, and lie sixth.
* Key man?
The midfielder Lukas Zelenka is the most experienced player. He is at the heart of most attacks for Sparta Prague. With endless energy, he helps out tirelessly in defence as well.