In the first leg, Arsenal boss Arsene Wenger took the rare but eminently sensible approach of making sure they remained in the tie by being defensively resolute and showing very little attacking ambition. The defence that had been repeatedly carved open by Eden Hazard, Cesc Fabregas and Alvaro Morata in the Premier League match a week earlier was protected from a similar fate by a deep-lying midfield that denied any space in which Chelsea's forwards could operate. But in the second leg Wednesday, in front of their own fans, the onus will be on Arsenal to come out and win the tie.

By its very nature, attacking football will leave gaps that opponents can exploit. Players can be caught out of position when possession is turned over, defences playing a high line can be punished by quick balls over the top and spaces can appear between the lines as teams choose to be expansive rather than compact. Arsenal could elect to play on the counterattack but that is not their preferred approach at the Emirates so there should be opportunities where Chelsea's forwards can prosper.

The key to the Blues' success will, inevitably, be the performance of Hazard. His all-round genius is well known as is his ability to convert the slightest of openings into a glaring chance. His man-of-the-match display at the Amex Stadium on Saturday might have come against a limited Brighton side though Hazard has also been equally devastating against far mightier teams, including Wednesday night's opposition.

Chelsea's injury situation, however, has placed even greater emphasis on the Belgian. Antonio Conte's revelation in Tuesday's news conference that both Morata and Fabregas will be unavailable means that his team will be denied the services of two of their principal weapons. Hazard might then become not just the primary but perhaps Chelsea's only real source of invention, at least in the centre of the field. Marcos Alonso and Victor Moses should still be able to create from the flanks.

It's a lot to ask of a player who has scored just once before at the Emirates -- a penalty in the 2-2 draw earlier this month -- though considering Hazard's god-given talent it is a responsibility he is perfectly capable of assuming. And it's not as if he hasn't damaged Arsenal before. In that same game he constantly ripped them to pieces and let's not forget his goal-of-the-season contender in the 3-1 win at Stamford Bridge last season. Hazard can draw upon plenty of fond memories of playing Arsenal.

As ever, any success Hazard has will depend on the combination of system and personnel that Conte selects. It was notable that his masterclass on Saturday came after the team reverted to 3-4-3 with Hazard excelling in the spaces created by the movement of extra attackers. However, his equally impressive performance against Arsenal in that 2-2 draw came in a 3-5-2. The vital ingredient that day was Fabregas, a player who could pull the strings and allow Hazard to play further up the pitch and take up all sorts of positions. Assuming that Conte plays that same system -- as he generally has done this season against strong opponents -- Chelsea's magician-in-chief might have to drop deeper to get on the ball if a midfield of N'Golo Kante, Tiemoue Bakayoko and Danny Drinkwater takes the field.

With that in mind, it would not be a total surprise to see Willian line up as the third midfielder alongside Kante and, presumably, Bakayoko. When the Brazilian was introduced for Drinkwater midway through the second half of the first leg, it was instructive that rather than take up his usual wide position, he instead slotted straight into the void left by the Englishman. Willian's inclusion in that role would mean that there was still a genuine creative element in midfield but without suffering the loss of an extra body in there. His pace also means that he could supplement the attack quickly and effectively, causing problems for Arsenal's defensive shape. He is also not shy about sticking his foot in even if he is hardly the most fearsome of tacklers.

Playing Willian in midfield would release some of the burden from Hazard and allow him to roam where he feels is necessary, which is always when he is at his most effective. Clearly, Chelsea will also need to be defensively sound and emotionally in check to succeed but if the Blues are to make it to Wembley, Conte needs to ensure that his best player is given every opportunity to flourish.