Busquets was injured during the second half of Barca's 3-0 win over Chelsea on 15 March (AEST), with tests subsequently confirming he had suffered a "fractured phalanx of the fifth toe of his right foot, with a wound".

As a result, he missed Spain's two friendlies in March and was also absent for Barca's 2-2 draw with Sevilla.

Although Barca rescued a draw at the Ramon Sanchez Pizjuan after being 2-0 down, Busquets's absence was plain to see, as it lost the midfield battle with Ivan Rakitic attempting to fill the void.

But Messi, who himself has been struggling with a muscular problem, came off the bench to salvage a point with an 88th-minute equaliser, and he, like Busquets, could be back in the starting XI for Roma's visit.

Valverde said: "Busquets trained yesterday in an important session and we think that today he will be fine.

"Tomorrow we think he'll be even better. He is a very important player for us because of his level.

"If Messi enters the squad list, he could play as a starter better than other games.

"The players are so good in their own position. When they are not missing, each one at their level, Busquets and Messi are fundamental players for us."

Messi has received some criticism back home in Argentina for not featuring in its two most recent friendlies, particularly for missing the latter against Spain, which ended up being a 6-1 defeat.

Valverde is ignoring such situations, however, adamant the world of football "is completely crazy".

"I do not know what happens in Argentina," Valverde said. "Messi is a unique player in the world and in history.

"This is the world of football, we already know how it is and that it is completely crazy."