Grant, appointed successor to Gianfranco Zola after the Italian was axed at the end of the season, has been keen to inject new life into a side which only just escaped relegation.

Barrera, who impressed at the World Cup, and Piquionne, whom Grant worked with at Portsmouth, will certainly do that, along with free transfer Thomas Hitzlsperger, the former Aston Villa midfielder.

And supporters were last night told to be braced for "further major additions.... within the next 72 hours".

Israel international Tal Ben-Haim, another of Grant's former Portsmouth players, is reported to be close to completing a switch to Upton Park, but it has emerged the Hammers now face competition from both Liverpool and Tottenham in the chase for £12million-rated Nice striker Loic Remy.

Nevertheless, in Barrera and Piquionne, Grants has acquired players who could have an major impact in the new season.

Barrera - a £4million signing from Pumas, after receiving his work permit yesterday - made three appearances at the World Cup, all as a substitute, as Mexico reached the last 16.

The 23-year-old intends to hit the ground running.

"The fans can expect that I will give 100% to succeed for the team and to play better than I have every played before," he said.

"I am very fast and can use both feet. I like the one-on-one situations and to take on my opponent and beat my rivals. I like to excite the supporters.

"People have said that I am the sort of player that the fans want to have the ball as often as possible because I can make things happen."

Piquionne, meanwhile, scored 11 goals in all competitions for relegated Portsmouth, with three of those coming in their run to the FA Cup final.

"Avram is a very, very good coach. Last year we had many problems at Portsmouth, but we got to the FA Cup final," said the 31-year-old.

"As a player, it will be good just to concentrate on my football. When I do that, I play well and play with passion. We have the players here to have a very good season."

The West Ham squad have now headed out to Germany, with all those involved at the World Cup - including England duo Robert Green and Matthew Upson - also joining up ahead of this evening's game with Borussia Monchengladbach.