Jonas hopes it will be Valencia who hold their nerve better in the race for Champions League football.
With Barcelona having secured the Primera Division title and the two Madrid sides clear in second and third, the main issue to be resolved at the top of the table is who will finish fourth.
Real Sociedad currently occupy the spot but are level on points with Valencia after only managing a draw against struggling Granada on Monday.
Sociedad looked to have gained a crucial advantage when they beat their rivals three weeks ago, but since then they have picked up only one point while Valencia have won both their games, most recently a 4-0 victory over Rayo Vallecano.
Striker Jonas has played a key role, scoring 10 goals in his last 11 games, and he told a press conference this week: "I was watching the game with my family and I was glad, because it is a result that helps us.
"Real Sociedad played a Granada side that needed a win to help avoid relegation. We also have tough games coming up but we will see who can hold their nerve the best. There are no easy matches.
"We know that the possibility of Champions League football increases every day, but we still don't have our fate in our own hands.
"We need more than just to win games. We know that they have the advantage in the event of a tie on points, but we are now level after clawing back five points. We have to take the nine remaining points as well."
Both teams are away from home this weekend, with Valencia taking on Getafe while Sociedad play Sevilla.
Malaga and Real Betis are in pole position to secure the remaining two places in the Europa League.
Malaga, whose finish to the season is being overshadowed by the future of boss Manuel Pellegrini, do not match have a match this weekend while Betis travel to bottom side Real Mallorca, who could be relegated if they fail to win.
Second-bottom Celta Vigo also look very vulnerable having played a game more than their rivals while Deportivo La Coruna, in 18th, meet Espanyol.
Real Zaragoza, who sit two points above the bottom three, will hope to move away from trouble with victory over Athletic Bilbao, while the two teams above Zaragoza, Granada and Osasuna, play each other.
For Barcelona, the remaining three games have no pressure attached, although nine points would bring up their century.
Despite the dominant nature of their title victory, it has been a season where Barca have slipped below their highest standards, but midfielder Xavi has urged the club not to make too many changes this summer.
Reflecting on his seventh league crown, the Spaniard told a press conference: "I could not have imagined winning so many titles. Our philosophy has yielded its rewards and I hope it continues to do so.
"We've set the bar very high and now it seems as though what we do falls short. We are competitive, we have to evaluate what we've done. It's not easy to win a title every season.
"I'm in favour of making few changes. It seems as though we're in a terrible situation and that we must change the whole team. But we're going through a good moment."