MILAN, Jan 28 (Reuters) - Juventus have signed Lazio defender Guglielmo Stendardo on loan for the rest of the season while Aston Villa's Olof Mellberg will join in July, the Serie A club said on Monday.Claudio Ranieri's side had also been expected to seal Mohamed Sissoko's transfer from Liverpool before the Mali midfielder headed back to the African Nations Cup in Ghana for a match agaist Ivory Coast on Tuesday. However, the deal has been delayed with a Juventus spokeswoman declining to comment on the hold-up. Sporting director Alessio Secco told Italian media the signing was very close and also said Portuguese midfielder Tiago would be staying at the club after Tottenham Hotspur ran out of time to conclude a deal. Third-placed Juve have a defensive injury crisis and have brought in Italian Stendardo after a move to recruit Sweden's Mellberg in the January transfer window stalled. Villa blocked an early deal but his contract runs out in June and the 30-year-old will be a Juve player for next season having penned a three-year deal, a Juventus statement said. "I am very happy with this agreement. Italy will be an important experience, at a prestigious club and in one of the most important championships in the world," Mellberg said. "Now I must finish the season in an Aston Villa shirt but I really can not wait to come to Juventus." Stendardo's move, signalled on the Italian club's website comes despite the defender being in the middle of a three-match league suspension. Lazio have replaced him by signing Dinamo Bucharest's Stefan Radu on loan for the rest of the season, the Romanian club's vice president Vasile Turcu told Realitatea television. Lazio's website confirmed his arrival with Turcu adding that the struggling Rome club would be able to sign the Romania defender permanently after the loan spell.