Portugal's forward and captain Cristiano Ronaldo (C) trains with teammates on June 7, 2014 in Florham Park, New Jersey

Cristiano Ronaldo handed Portugal a huge boost on Saturday as he returned to training after leg injuries that had threatened to wreck his World Cup.

The star forward has been struggling for weeks with thigh and knee injuries that forced him out of Portugal's last two warm-up matches and raised fears he might miss the start of the Brazil tournament.

Portugal kick off their World Cup campaign against Germany on June 16 in Group G, which also features the USA and Ghana.

The 29-year-old Ronaldo took part in training with the rest of the Portugal squad in New Jersey, in the United States, and could be in line for a return to competitive action on Tuesday in a friendly with Ireland.

Training was a tepid affair, with Ronaldo and his teammates doing stretching and passing drills for the media.

The Portuguese have toiled in the Real Madrid ace's absence, drawing 0-0 with Brazil-bound Greece last weekend and laboring against fellow World Cup qualifiers Mexico Friday before grabbing a 1-0 victory in injury time.

Experienced midfielder Raul Meireles also trained with the full squad on Saturday, while key defender Pepe, who missed his club Real Madrid's Champions League victory because of injury, stepped up his return but remains on a separate rehabilitation program.

Coach Paulo Bento has not hidden his frustration at the constant speculation over the availability of Ronaldo, who has scored 49 goals in 110 matches for Portugal.

"Ronaldo is not the only good player we have," he snapped on Thursday.

But on the evidence of Friday's barely deserved victory -- thanks to a powerful header from stand-in skipper Bruno Alves -- Portugal will need Ronaldo at his brilliant best if they are to make an impact in Brazil.