English rivals Arsenal and Chelsea were drawn to meet each other in the pick of the Champions League quarter-finals.
Victory for Barcelona took them to within a point of third-placed Deportivo Coruna and kept second-placed Valencia in their sights.
"We can still turn the contest around," the Juventus captain said after the defeat by Deportivo La Coruna.
Iniesta has spent all of his senior career at Barcelona and is their most decorated player ever along with Lionel Messi, having lifted 31 trophies, which is soon to be 32 if Barca clinch the Liga title on Sunday at Deportivo La Coruna.
A last-gasp strike from Ronaldo helped his side snatch a 3-2 win at Valladolid.
He scored twice in a 4-2 win over Barcelona in the Spanish League.\n\n
They drew 1-1 with PSV Eindhoven to make sure of a berth in the pre-quarter-finals of the Champions League.
Chasing duo Valencia and Real Madrid will have a chance to draw level if they win their matches on Sunday.
The Manchester United midfielders have knee injuries and will miss Champions League matches against Basel and Deportivo Coruna.
Real, bidding for a 10th European Cup, have the easiest task on paper away to a Partizan Belgrade side.\n\n
The Spanish League leaders slipped to a 2-0 defeat at home to Real Mallorca.
Depor's two Barcelona-born players scored in each half to secure victory at the Nou Camp.
They joined Valencia and Stuttgart on top of their respective divisions after weekend action in Europe's main leagues.
The victory sent Valencia to the top of the Spanish league.
Cristiano Ronaldo has accepted that he needs to rest more and that sitting out the odd game is in the interests of him and Real Madrid, coach Zinedine Zidane said on Friday. Real's all-time top scorer has missed four of his team's 15 league games this season, two more than in the whole of the last campaign, and he was a surprise omission from the squad for Wednesday's King's Cup game against Sevilla. Zidane remarked last year that he would prefer Ronaldo to rest more after injuries forced him to miss vital games at the end of the season, although the Frenchman appears to have reached agreement with his talisman this campaign.
Cristiano Ronaldo continued his prolific start to the season with four goals, including two penalties, as Real Madrid came from behind to beat Elche 5-1 in La Liga on Tuesday.
The two forwards have hit their strides ahead of Saturday's Clasico showdown between the two heavyweight clubs.
Atletico Madrid will face holders Real Madrid in the last 16 of the King's Cup after a double from Mario Mandzukic sealed a 5-2 aggregate victory over lower league Hospitalet on Thursday.
Deportivo title hopes suffered a serious setback when they were beaten 2-1 at home to Valencia.
Real Sociedad moved above Real Madrid into second place behind leaders Deportivo after a 3-1 win over an in-form Real Mallorca in the Spanish League.
Real have frittered away a four-point cushion at the top of the Spanish League in the space of just two games.
The 1-1 draw put Real four points clear at the top of the table.\n\n
Cristiano Ronaldo will play no part in Real Madrid's game against Deportivo La Coruna on Saturday after the prolific Portuguese forward was left out of the squad on Friday.
Atletico Madrid secured a berth in the Champions League group stage for next season and Deportivo La Coruna narrowly escaped relegation when they came from two goals down to draw 2-2 at champions Barcelona on the final day in La Liga on Saturday.
Defender Cesar has been banned for four matches by the Spanish Football Federation for head-butting Villarreal striker Antonio de Nigris in a league match
Lionel Messi scored a hat-trick as Barcelona clinched a 25th La Liga title on Sunday after winning 4-2 at Deportivo La Coruna despite throwing away a two-goal lead in a thrilling game which also confirmed Depor's relegation.
Real Madrid beat Leganes 2-1 in La Liga on Saturday after coach Zinedine Zidane heavily rotated his side in preparation for Tuesday's Champions League semi-final second leg against Bayern Munich, including leaving out top-scorer Cristiano Ronaldo.
A 2-1 victory enabled Real extend their perfect home league record and stay two points clear at the top of the table in the Spanish League. \n\n
A Real Madrid vice president has admitted unspecified problems have delayed the signing of Tottenham Hotspur's Gareth Bale although he predicted the deal would be agreed before the transfer window closes next week.
Real Madrid ensured top spot in La Liga at the midway point of the season when Cristiano Ronaldo struck twice in a 3-0 win at Getafe on Sunday before Lionel Messi's hat-trick helped Barcelona to a 4-0 victory at Deportivo La Coruna.
It is a scenario few could have foreseen after Real won a Liga and Champions League double last term and began this season so convincingly.
A first half Tiago header set up Atletico Madrid's 2-0 victory over Espanyol as they seek to get back on track following a stuttering start to the La Liga season.
Marcelino dismissed but Valencia keep pressure on Barcelona